IB Biology Year 1 Midterm Review Questions (2025) - PDF

IBDP Biology (2025) Basic Knowledge Questions by Christian Moore-Anderson, author of Difference Maker: Enacting Systems Theory in Biology Teaching IBDP Biology 2025 Basic Knowledge Questions Odyssey - Year 1 - Midterm By Christian Moore-Anderson A2.3 Viruses A1.1 Water D2....

IBDP Biology (2025) Basic Knowledge Questions by Christian Moore-Anderson, author of Difference Maker: Enacting Systems Theory in Biology Teaching IBDP Biology 2025 Basic Knowledge Questions Odyssey - Year 1 - Midterm By Christian Moore-Anderson A2.3 Viruses A1.1 Water D2.3 Water potential B1.1 Carbohydrates and lipids B1.2 Proteins C1.1 Enzymes and metabolism A2.1 Origins of cells A2.2 Cell Structure - Microscopy B2.1 Membranes and membrane transport B2.2 Organelles and compartmentalisation B2.3 Cell specialization A1.1 Water What physical and chemical properties of water make it essential for life? What are the challenges and opportunities of water as a habitat? 1. Name four properties of water that are It is an excellent solvent (can dissolve many things) useful for life It is transparent to light It has a high specific heat capacity (requires a lot of energy to heat) Ice is less dense than water (it floats) 2. Draw the molecular structure of water forming H bonds with two other water molecules. Label: Relative charges, the H bonds, and the covalent bonds 3. State the difference between cohesion & Cohesion: Water molecules are attracted to each other adhesion Adhesion: Water molecules are attracted to other charged molecules 4. State the relationship between the number More hydrogen bonds increase the boiling point of hydrogen bonds a small molecule →more energy (heat) is required to separate the molecules can form and its boiling point, and why 5. What is the relationship between the The more charges or polarity, the increased ability to dissolve in water charge or polarity of a molecule and how easily it dissolves in water? 6. Give the name for substances that can Hydrophilic substances (With polarity or a charge) dissolve in water and give three examples Glucose, amino acids, ions found in life 7. Give the name for substances that cannot Hydrophobic substances (with no charge or polarity) dissolve in water and give two Fats, steroids (lipids) examples found in life 8. Compare the similarities and differences Similar: both small molecules with covalent bonds with H of methane to water, and give two Different: methane is non-polar and doesn’t form H-bonds consequences of methane’s difference →so methane has a very low boiling point (evaporates easily) →so methane can’t dissolve hydrophilic molecules 9. Contrast the consequences of living in Water conducts heat more easily --> causing more difficulty in water to living in air with regards to: maintaining a higher temperature when living in water—than in air thermal conductivity 10. Contrast the consequences of living in Water has a higher specific heat capacity --> causing ambient water to living in air with regards to: temperature changes to be more stable—than in air specific heat capacity 11. Contrast the consequences of living in Water has a higher viscosity --> causing lateral movement through water to living in air with regards to: water to be more difficult—than in air viscosity 12. Contrast the consequences of living in Water produces more buoyancy --> causing floating and vertical water to living in air with regards to: movement in water to be easier—than in air buoyancy. 13. State possible origin of the water on Earth Extra-planetary water was brought by asteroids that collided with Earth 14. Give two reasons for why water was 1. Strong enough gravitational field retained on Earth 2. Temperatures low enough for water to condense into a liquid—not hot enough for it to vaporize 15. Why is Earth said to be in a ‘goldilocks’ The distance from the Sun - temp. is not too cold (water freezes over zone? all of Earth), nor too hot (water evaporates across most of Earth) A1.2 Nucleic Acids How does the structure of nucleic acids allow hereditary information to be stored? How does the structure of DNA facilitate accurate replication? 16. Name the three components of a Nitrogenous base, pentose sugar, phosphate group nucleotide 17. Draw the structure of DNA and annotate it with these details: Phosphate group, ribose, nitrogenous base Antiparallel 5’ to 3’ Adenine, thymine, guanine, cytosine Hydrogen bonds Phosphodiester bonds (covalent) 19. State three differences between DNA & RNA is single stranded—DNA is double stranded RNA RNA uses the base ‘uracil’—DNA uses the base thymine RNA nucleotides have ribose—DNA nucleotides have deoxyribose 20. Draw the difference between a DNA & RNA nucleotide 21. What feature of DNA allows it to be Complementary base pairing replicated easily? 22. What is complementary base pairing in Adenine binds with thymine DNA? Guanine binds with cytosine Because their shapes and charges match 23. Give three reasons for how DNA is It can be endlessly long (& have different lengths) a good structure for storing information Base sequences can have infinite varieties DNA is incredibly thin (large storage in a tiny space) 24. If all organisms on Earth use DNA, All life on Earth is related and there is a universal common what does this suggest? ancestor (some viruses use RNA but are not considered alive) 25. State which bases are purines & Purines—A & G (remember it this way “pure silver”) which are pyrimidines Pyrimidines—T & C 26. State a similarity between A-T pairs Both are the same length and G-C pairs Because both contain a purine (smaller) and a pyrimidine (larger) 27. State why different base sequences All complementary base pairs have a purine (smaller) with a maintain the same 3D structure of DNA pyrimidine (larger) So the overall structure is always the same 28. State how eukaryotic DNA is organized Wrapped around histone proteins to make a nucleosome & wrapped in the nucleus Nucleosomes bunched together form chromatin fibre 29. Draw two nucleosomes 30. How thick is a DNA strand, and how DNA: 2nm thick is chromatin fibre? Chromatin: 30nm 31. How many proteins make up the 8 histones nucleosome? 32. What ensures that DNA is attracted to Opposing charges histone proteins? DNA is negatively charged Histones are positively charged 33. What joins one nucleosome to another? Linker DNA 34. What method is used to further Supercoiling condense DNA into visible chromosomes? 35. What was the purpose of the experiment To establish whether DNA or protein was the hereditary material of life carried out by Hershey and Chase 36. Give two reasons why scientists Proteins were thought to contain more complexity because they originally thought protein, and not have twenty different amino acids compared to four nucleotides of DNA, was the DNA hereditary material of life The tetranucleotide hypothesis stated that DNA was simply a repeating structure of the four bases (so cannot store information) 37. State the two modifications Hershey & The protein was labelled with radioactive sulphur Chase made to the phage (viruses) in The DNA was labelled with radioactive phosphorus the experiment to be able to ‘see’ them 38. Describe what happened when the The phage infected the bacteria & inserted their DNA inside phage were mixed with bacteria and →The bacteria were then separated from the phage how this was known by Hershey & parts outside →The radioactive DNA remained in the Chase bacteria 39. How did Hershey & Chase separate They centrifuged the sample the DNA from the protein? The denser bacteria (with DNA inside) went to the sediment, with the protein above (supernatant) 40. What technological advancement The production and availability of radioisotopes as research tools allowed for Hershey and Chase’s experiment to take place? 41. State Chargaff’s rule %A = %T %G = %C 42. How did Chargaff’s rule falsify the If the tetranucleotide hypothesis were true, % of each nucleotide tetranucleotide hypothesis would be equal Data of DNA showed Chargaff’s rule to be correct and relative quantities were different 43. How did Chargaff’s rule provide Unlike the tetranucleotide hypothesis, Chargaff’s rule showed evidence that DNA could store that the base sequence can vary (does not simply repeat) information A2.1 Origins of cells What plausible hypothesis could account for the origin of life? What intermediate stages could there have been between non-living matter and the first living cells? 44. Name the three main points of cell theory Living organisms are composed of cells Cells are the smallest units of life Cells come from pre-existing cells 45. State three major similarities between They are composed of organic molecules cells & viruses They store information in nucleic acids They can evolve 46. State two major differences between Cells are self-sustaining systems—viruses can’t do this without cells & viruses other cells Cells are self-reproducing systems—viruses can’t do this without other cells 47. State how conditions on early No atmospheric oxygen—More carbon dioxide & methane Earth were different to now No ozone layer—so much more UV light Warmer 48. How could early Earth conditions Warmer temperatures & more UV light could have provided the energy have contributed to conditions for for organic compounds to form cells emerge? 49. What did the Miller-Urey experiment That amino acids could be formed in the presence of lightning and show? a soup of simpler inorganic molecules 50. State three cons of the Miller-Urey It made assumptions about early Earth’s atmosphere that are experiment now disputed It didn’t produce all the essential organic molecules used by life It didn’t show how amino acids could be assembled into larger molecules 51. Why was the evolution of a membrane Creates a barrier so that the inside of a cell can be made different to essential for the first cells? the external environment 52. What aspect of fatty acids suggests that In water, fatty acids spontaneously form spherical vesicles membranes might have formed Because they are both hydrophobic and hydrophilic spontaneously? 53. What conditions were necessary inside Catalysis (like the action of enzymes) of chemical reactions that the cell for life to emerge? produce the molecules needed to build the cell The self-assembly of the molecules to form the cell’s structures 54. State two problems with testing The exact early Earth conditions cannot be replicated in the lab hypotheses about the origin of cells The first protocells did not leave any fossil evidence 55. State two reasons why one hypothesis RNA can store information & act as a catalyst (like an enzyme) suggests RNA—not DNA—was the first Ribozymes at the core of ribosomes are still used to catalyse protein genetic material synthesis 56. State three pieces of evidence that All organisms use the same—universal—genetic code suggests all life on Earth are decedents of Some genes are shared across all organisms LUCA (last The structure and function of ribosomes is similar in all organisms universal common ancestor) 57. What evidence exists that supports the Fossils of ancient life near hydrothermal vents hypothesis that LUCA evolved around Extremophile prokaryotes exist today that can survive in similar seafloor hydrothermal vents? conditions Conditions in hydrothermal vents have similarities to early Earth (e.g. anaerobic) Hydrothermal vents are rich in energy sources, such as hydrogen gas, methane, and reduced metals A2.2 Cell structure What are the features common to all cells and the features that differ? How is microscopy used to investigate cell structure? 58. State the three principal structures Genetic material consisting of DNA that are typical of all cells Cytoplasm consisting mainly of water Plasma membrane consisting of lipids 59. Name the three main points of cell theory Living organisms are composed of cells Cells are the smallest units of life Cells come from pre-existing cells 60. State the processes of life that —Homeostasis (maintaining stable internal conditions—to unicellular organisms generally persist) via: —Metabolism (chemical reactions) by way of: undertake (1. inputs & outputs of energy & matter)—Nutrition & Excretion (2. responsive behavior & development)—Movement, Growth, Response to stimuli, and Reproduction 61. Draw & annotate a typical prokaryote cell 62. Draw & annotate a eukaryotic cell with structures that are typical of eukaryotes 63. State the difference in cell walls in Animal—Not present, Fungi—Composed of chitin animal, fungal, plant cells Plant—Composed of cellulose 64. State the difference in size & Animal—Not common, small, storage of waste function of vacuoles in animal, fungal, Fungi—Large, maintain turgor pressure, storage plant cells Plant—Large, maintain turgor pressure, storage 65. State the difference in the presence of Animal—Not present, Fungi—Not present plastids in animal, fungal, plant cells Plant—Chloroplasts & other plastids present 66. State the difference in centrioles, cilia, & Animal—All common, Fungi—Absent, Plant—Absent flagella in animal, fungal, plant cells 67. Give four examples of eukaryotic Striated muscle—very long, multinucleated cells cells with atypical numbers of Aseptate fungi—multinucleated with no clear boundaries nuclei between cells Mammalian red blood cells—no nucleus Phloem sieve tubes—no nucleus A2.3 Viruses How can viruses exist with so few genes? In what ways do viruses vary? 68. Name the structural features shared by Small, Genetic material is nucleic acid (DNA or RNA) viruses Protein capsid, No cytoplasm, & few (or no) enzymes 69. State four ways that viruses vary Genetic material—Can be DNA or RNA, double-stranded or single-stranded Shape Can be enveloped by membrane (taken from host cell) or not enveloped 70. Give three examples of viruses & their HIV—single-stranded RNA genome type Coronaviruses—single-stranded RNA Bacteriophage lambda—double-stranded DNA 71. Describe the phases of the lytic 1. Attachment—The phage binds to the bacterial surface cycle of bacteriophage lambda 2. Entry of DNA—Viral DNA is injected & bacterial DNA is hydrolysed 3. Protein synthesis—The cell transcribes and translates viral DNA 4. Self-assembly—Viral proteins self-assemble into phage 5. Release—The cell lyses releasing the new phage 72. Describe the phases of the lysogenic 1. Integration of DNA—phage DNA is integrated into the bacterial cycle of bacteriophage lambda chromosome (becoming a prophage) 2. Multiplication—phage DNA is replicated every time the prophage divide 3. Entry into lytic cycle—Certain environmental factors can shift the prophage into the lytic cycle 73. State three ways the lysogenic cycle is 1. In the lysogenic cycle bacterial DNA is not hydrolysed different to the lytic cycle 2. In the lysogenic cycle viral DNA is integrated with the bacterial chromosome 3. In the lysogenic cycle viral DNA is replicated with bacterial DNA 74. What is an advantage of lysogenic cycle? Viruses are able to propagate without killing their host cells 75. What aspect of viruses suggest they Viruses and living organisms share the genetic code evolved from living organisms? 76. What aspects of viruses suggest Similarities in the capsid structure—must have evolved under convergent evolution of viruses (not similar selective pressures divergent)? Similarities in life cycles—an extreme form of obligate parasitism 77. What does the vast diversity of viruses They evolved many different times from different living organisms suggest about their origins 78. Give four reasons for why viruses can Very short generation times evolve rapidly High mutation rate Very large populations Viral genomes can recombine with other viral genomes 79. Give two examples of how If two different viruses infect the same cell… recombination of genomes occurs in —Compatible chromosomes can exchange sections of DNA viruses? —Compatible genomes can recombine different segments of a genome (if they are segmented) 80. Explain one reason why influenza They have a segmented genome viruses are able to evolve rapidly If two or more influenza viruses infect the same cell, the genomes can reassort to have different combinations of the segments 81. Explain one reason why HIV viruses are They have an RNA genome & its reverse transcriptase enzyme lacks able to evolve rapidly proofreading Causing high mutation rate in the resulting DNA 82. State three consequences for treating Rapid antigenic changes may make vaccine development more diseases caused by rapidly evolving viruses difficult Rapid evolution may make viruses resistant to treatments quickly Rapid evolution causes a need for more resources for constant monitoring (DNA sequencing) & controlling spread A3.1 Diversity of organisms What is a species? What patterns are seen in the diversity of genomes within and between species? 83. How are species names composed and Genus name & species name give the example of our species name Homo sapiens (in italics) 84. How did Linnaeus originally classify Originally by their shared morphological traits (the Typological organisms and how is it done now? Species Concept) Now by DNA sequence (or amino acid sequence) & evolutionary history 85. State the biological species concept A species is a group of organisms than can breed and produce fertile offspring 86. What is the principal problem with While there is variation between different species, there is also classifying organisms into groups variation within species 87. Why is the classification of two Populations that reproductively isolated diverge gradually (slowly populations into two species often an becoming more and more different) “arbitrary” decision? When they become different species is often just a person’s decision 88. Give an example where the classification When there are two isolated populations of the same species that system with the biological species are slowly evolving to be different, it is unsure whether they can concept doesn’t work well breed to form viable offspring 89. State the principal difference between Biological SC—related populations are different species when there is the biological species concept and the reproductive isolation phylogenetic species concept Phylogenetic SC—related populations are different species when they differ in a trait or in a gene (differing alleles—normal—is not a different species) 90. State two disadvantages of the —Populations exhibit variation, so would lead to dividing species into phylogenetic species concept many more species —Defining difference in traits is subjective 91. Name the three domains of life and Bacteria (prokaryotes), Archaea (prokaryotes), Eukarya (eukaryotes) state whether they are prokaryotes of eukaryotes 92. What is a genome? The entire set of DNA found in an organism 93. What is a proteome? The set of proteins found in a cell (showing which genes are expressed) 94. State two differences between the Prokaryotes have one circular chromosome of DNA, but eukaryotes genomes in prokaryotes and have multiple linear chromosomes eukaryotes? Eukaryote genomes are larger than prokaryote genomes 95. What trait of the genome is the Chromosome number same in all members of a species? 96. State the (diploid) chromosome Humans 46, chimpanzees 48 number of humans and chimpanzees 97. Name three factors that help Length, centromere position, banding patterns scientists to classify chromosomes 98. State three pieces of evidence that 1. Chromosome 2’s sequence is almost identical to chimpanzee supports the hypothesis that human sequences found on two different chromosomes (also true for gorillas chromosome 2 originated from a fusion of and orangutans) chromosomes 12 and 13 in an ancestor 2. Chromosome 2 has one centromere, and one remnant of a centromere 3. Chromosome 2 has the remnants of telomeres in the middle of the chromosome 99. What differences can be found in the Single nucleotide polymorphisms (SNPs) (due to mutations) genome of members of the same species? 100. What is a gene? A DNA sequence that codes for a protein or an RNA 101. What is an allele? A version of a gene (with different SNPs) 102. What genetic material should be the Genes: same same and different between two Alleles: different individuals of the same species? 103. What’s the relationship between the The more recent the common ancestor, the more genes they share number of genes shared by two species and their common ancestor? 104. What relationships exist between Eukaryotic organisms are more complex & have larger genomes than genome size and organism prokaryotes But there isn’t a relationship within eukaryotes complexity? 105. Give two benefits of carrying out Personalized medicine, researching evolutionary relationships whole-genome sequencing of organisms 106. State why cross-breeding between Might have an odd number of chromosomes, which cannot be closely related species typically halved to form haploid gametes produces infertile offspring 107. Give a reason why the biological They don’t form interbreeding populations so do not produce fertile species concept has difficulties with offspring from two parents/gametes classifying asexual species 108. Give two reasons why the biological Prokaryotes are asexual, and they pass genes between different species concept has difficulties with species in ‘horizontal gene transfer’ classifying prokaryotes? 109. What is DNA barcoding? A method of identifying species by comparing short sequences of DNA with a database of fully sequenced genomes 110. What is eDNA? Environmental DNA which is found in samples (e.g. water, soil) 111. What is the benefit of using DNA Biodiversity can be investigated rapidly and is non-invasive barcoding with eDNA? A3.2 Classification & cladistics What tools are used to classify organisms into taxonomic groups? How do cladistic methods differ from traditional taxonomic methods? 112. Name the taxa used to classify Domain, kingdom, phylum, class, order, family, genus, species organisms from the most encompassing (King Phillip came over for good soup) down to the species 113. What alternative does cladistics Unranked groups (clades) that reflect the true variation of species offer classification that the (rather than ranked groups that all species must fit into) tradition hierarchy doesn’t? 114. What is a clade? A group in which all members descend from a common ancestor 115. What can knowledge of a clade and its Shared characteristics members help you predict? 116. What evidence is used for placing DNA or amino acid sequences species in clades? Morphological traits 117. What evidence was used to add the Ribosomal RNA sequences (rRNA) extra taxonomic level of domain (above kingdoms)? 118. What is a molecular clock? A method of estimating evolutionary times between species and common ancestors 119. How does the molecular clock method It uses an estimate of the mutation rate and then compares the work? differences in DNA sequences of two species 120. What are the problems with the Mutation rates can vary—are not constant molecular clock method? 121. Name three factors that affect mutation The generation time, the size of a population, and the intensity of rates selection acting on a population A4.1 Evolution & speciation What is the evidence for evolution? How do analogous and homologous structures exemplify commonality and diversity? 122. Name the four main pieces of evidence Comparing genomes or gene sequences we have for evolution Fossil record Artificial selection / selective breeding Comparative anatomy showing homologous structures 123. Name two things that the fossil record A gradual change in the traits of an organism over time. shows us about evolution Intermediate forms. 124. What is the method in which fossils Carbon dating can be dated? 125. Give two ways that artificial selection / It shows that the heritable traits of a species can change selective breeding provides evidence for over time It shows that evolution can happen rapidly evolution? 126. How does comparative anatomy give Homologous structures suggest common ancestry evidence for evolution? 127. What is a homologous structure? Structures in different species that are similar in form → because they have been inherited from the same common ancestor 128. Give an example of a homologous Pentadactyl limb in tetrapods (humans, bats, whales, birds, structure amphibians, reptiles, etc) 129. What is convergent evolution? The evolution of similar traits in species of different clades. 130. What is an analogous structure? Structures in different species that have evolved to be similar in form →but evolved independently (not from a common ancestor) 131. Give an example of convergent Wings in birds, bats, and flying insects evolution / analogous structures Or: Fins in fish, mammals, and penguins 132. If different species have analogous The structure was not present in their common ancestor structures from convergent evolution what does this suggest about the structure and their common ancestor? 133. What is speciation? The accumulation of differences between related populations that leads to the formation of two species 134. What increases, and what Speciation increases the number of species decreases the number of species on Extinction decreases the number of species Earth? 135. What is the cause of speciation? Reproductive isolation between two populations (inhibiting the flow of genes between them) 136. What caused the speciation event The formation of the Congo River 2 million years ago created a barrier to that led to chimpanzees and gene flow (reproductive isolation) bonobos? 137. What is allopatric, and sympatric Allopatric: A geographical barrier physically isolates populations speciation? causing speciation Sympatric: Speciation within the same geographical location 138. What is reproductive isolation? Any difference between populations that reduces gene flow (little exchange of genes) 139. What types of reproductive isolation Behavioural isolation (e.g. Individuals begin selecting mates can occur in sympatric speciation? differently) Temporal isolation (e.g. individuals begin breeding at different times) 140. Give two genetic causes for Different selection pressures acting on each population speciation in two reproductively isolated Different mutations occur in each population populations 141. At what moment is it generally When differences between two populations prevent interbreeding to considered that speciation has produce viable offspring occurred? 142. What pre-reproductive barriers exist that Courtship behavior may now be different, so mating doesn’t occur prevent two related species from becoming one species again? 143. What post-reproductive barriers exist Hybrid offspring can be infertile (e.g. mules) that prevent two related species from becoming one species again? 144. What is adaptive radiation? Organisms diverge rapidly from a common ancestor into many new species 145. In what conditions does adaptive Many different niches become available radiation normally occur? 146. What is polyploidy? When an organism (or cell) has more chromosome pairs than 2n (>diploid) 147. Why does polyploidy often lead to The polyploid organism cannot reproduce with the original non-polyploid speciation? organism 148. Give an example of a plant genus that Knotweed (genus Periscaria) has many polyploid species. Onion family (genus Allium) 149. What is the main mechanism for Failure of reduction (of chromosomes) in meiosis producing polyploids? →which causes unreduced gametes A4.2 Conservation of biodiversity What factors are causing the sixth mass extinction of species? How can conservationists minimize the loss of biodiversity? 150. Name three levels of biodiversity Ecosystem—the variety of ecosystems on the Earth Species—the variety of species in a community Genetic—the variety of alleles in a population 151. Describe the two factors that form the Species richness: The total number of different species in concept of biodiversity of species an area Species evenness: The relative abundance of the species in an area 152. According to fossil evidence, what is the General trend is that biodiversity has been increasing since the general trend of biodiversity over geological origin of life (Speciation > extinction on average) time? 153. State the general cause of the Human population growth current biodiversity crisis 154. State five specific causes of the 1. Hunting (& overexploitation of populations) anthropogenic biodiversity crisis 2. Urbanisation 3. Loss of habitats due to deforestation & agriculture 4. Pollution 5. Introduction of invasive species and disease 155. Give an example of a marine species Caribbean monk seals driven to extinction and state the Were hunted to extinction by humans (for blubber and oil) anthropogenic factors for why 156. Give an example of a terrestrial Giant Moa of New Zealand megafauna species driven to extinction and Were hunted to extinction by humans (for food and tools) state the anthropogenic factors for why 157. Give an example of ecosystem loss in Desertification of south-east Iberia Iberia due to anthropogenic activity Due to poor agricultural practice 158. Give an example of ecosystem loss in Loss of mixed dipterocarp forest in Southeast Asia Asia due to anthropogenic activity Due to deforestation, logging, & agricultural expansion 159. What can be accepted as evidence of Repeated biodiversity surveys from a wide range of habitats around the a biodiversity crisis? world 160. Give a pro and con of surveys Pro: very large data collection for free carried out by citizen scientists Con: method of data collection might not be reliable 161. State the difference between in situ In situ: conservation of species with their natural habitat and ex situ conservation Ex situ: conservation of species in an artificial environment 162. Give two examples of types of Nature reserves, Rewilding degraded ecosystems in situ conservation 163. State two advantages of in situ The species has all the resources they are adapted (& evolve to) conservation Large populations can be maintained 164. State two disadvantages of in situ Difficult to monitor & protect the population conservation Species close to extinction are harder to conserve 165. Give three examples of types of Captive breeding (e.g. zoos), Botanical gardens, Seed banks ex situ conservation 166. State an advantages of ex situ Greater control of conditions can increase reproduction rate conservation 167. State three disadvantages of ex situ Does not prevent the destruction of natural habitats conservation Species are less likely to be successfully reintroduced into the wild Increases inbreeding and restricts the evolution of the species 168. What is rewilding? Reintroducing the variety of functions to ecosystems By introducing species that are similar to extinct species that once lived there 169. What species are prioritised by the Evolutionary distinct—unusual & with few close relatives EDGE of existence programme (irreplaceable) Globally endangered 170. State four ways that evidence Repeated measures over time of: for the biodiversity crisis is Genetic diversity in a species collected Population size of a species Species diversity (richness and evenness) in an ecosystem Ecosystem area B1.1 Carbs & lipids In what ways do variations in form allow diversity of function in carbohydrates and lipids? How do carbohydrates and lipids compare as energy storage compounds? 171. How is a covalent bond different to Covalent—Strong bond created by sharing electrons an ionic bond and hydrogen bond? between atoms Ionic—Strong bond created between ions that have opposite charges H-bond—Weak bond caused by attractions between atoms that are polar 172. How many covalent bonds can carbon 4 bonds in total (which can be in single or double bonds) form in total? 173. What is the difference between a Single—one electron is shared by each atom single and double covalent bond? Double—two electrons are shared between each atom 174. State two reasons for why life is Carbon is common based on carbon compounds Carbon can form complex (stable) structures (due to forming 4 bonds) 175. Name three disaccharides & their Lactose: glucose & galactose monosaccharides Sucrose: glucose & fructose Maltose: glucose & glucose 176. State the difference between a Pentose—5 carbon monosaccharide—Ribose pentose and a hexose & give an example Hexose—6 carbon monosaccharide—Glucose of each 177. State four properties of glucose that It’s soluble (due to many OH groups), therefore… make it a good molecule to be used by life Transportable (in water) It’s chemically stable (typically doesn’t react much with other molecules of cells) But yields lots of energy when oxidised (which can be controlled in cells) 178. What is the name of the reaction for Condensation reaction (releases water) forming polymers from monomers? 179. What is the name of the reaction for Hydrolysis reaction (splitting using water) breaking down polymers into monomers? 180. Name the polysaccharide used for Glycogen storage in animals and what it is Composed of alpha-Glucose monomers composed of. 181. Name the polysaccharide used for (Starch) Amylose, & amylopectin storage in plants and what it is composed Composed of alpha-glucose monomers of. 182. What is the name of the bond used for alpha 1-4 links (glycosidic) forming long chains in amylose, amylopectin, and glycogen? 183. What type of bond is used to start a alpha 1-6 links (glycosidic) new branching chain in amylopectin, and glycogen? 184. State a similarity and difference Both are polysaccharides of alpha-glucose between the two types of starch Amylopectin has more branching than amylose 185. State the relationship between the An increase in branches increases the rate at which it can be hydrolysed / extent of branching in polysaccharides digested and the rate at which they can be hydrolysed to their monomers 186. State how the branching structure of Glycogen’s many branches can be hydrolysed quickly to glucose glycogen relates to its function →to function as a quick access energy store 187. State three reasons why Polysaccharides can be stored as compact structures due to coiling organisms have evolved to store and branching Polysaccharides are too large to be soluble & don’t carbohydrates in polysaccharides and interfere with osmotic balance Adding & removing glucose is relatively not as monosaccharides. easy through condensation and hydrolysis 188. Where is cellulose found in life? Plant cell walls 189. State three ways that cellulose is Cellulose chains are straight—amylose chains for spirals different to amylose Cellulose is formed from beta-glucose—amylose is formed from alpha-glucose Cellulose’s glucose molecules alternate in orientation—in amylose they don’t 190. State how the structure of cellulose Cellulose chains have outward facing OH groups that form hydrogen makes it ideal for forming fibers with bonds with other cellulose chains other cellulose chains. 191. What is the name of the bond used for Beta 1-4 links (glycosidic) forming long chains in cellulose? 192. State a functional role of As a component of glycoproteins, which are used in cell-cell carbohydrates (aside from cellulose, recognition e.g. the ABO antigens found in A, B, and O blood or energy storage) & give an example groups 193. Give four examples of lipids Fats, oils, waxes, steroids 194. State two things that lipids have in —Molecules of living organisms that are hydrophobic common (don’t dissolve in water, but will dissolve in other hydrophobic substances) —Many C-H bonds 195. Draw a saturated fatty acid 196. How many double bonds do these Saturated: None fatty acids have: Saturated, Monounsaturated: One Monounsaturated, Polyunsaturated: More than one Polyunsaturated 197. What are the components of a 1 glycerol with… triglyceride? 3 fatty acids 198. What are the components of a 1 glycerol with… phospholipid? 2 fatty acids & 1 phosphate group 199. How are fatty acids bonded to glycerol? Condensation reaction 200. What is the relationship between the The more double bonds—The less viscous (runnier) number of double bonds and the viscosity of a fat? 201. What is the relationship between the The more double bonds—The lower the melting point (more likely to be a number of double bonds and the melting liquid) point? 202. State the major difference in Fats—more saturated fatty acids composition in fats and oils Oils—more unsaturated fatty acids 203. What is the difference in energy Fats have twice the energy content of carbs for the same mass (per content (per gram) in fats and carbs? gram) 204. State two advantages of organisms Triglycerides store more energy per gram (than carbs or storing energy as triglycerides and why amino acids) →more energy can be stored for a lighter weight Fats are hydrophobic (do not dissolve) and are stable molecules →can be stored long-term without causing problems with osmosis or reactions 205. Why do many mammals store Adipose tissue acts as thermal insulation, helping with thermal triglycerides in adipose tissue at the homeostasis surface of the body? 206. Why do endotherms store fats high in Endotherms maintain a high body temperature, at which saturated saturated fatty acids? fatty acids remain as solids, but unsaturated fatty acids form liquids 207. Explain the advantages of organisms Carbohydrates are hydrophilic & easily transported (in storing energy as carbohydrates blood, or sap) →good for a quick access, short-term store of energy 208. What molecule is used in animals for Fats (triglycerides) in adipose tissue long-term storage and where is it stored? 209. What molecule is used in animals for Glycogen in liver and muscle tissue short-term storage and where is it stored? 210. Where do plants store energy as fats, In seeds and why? → more energy can be stored in a lighter seed 211. Where do plants store energy as In storage organs (like tubers) carbohydrates? 212. What does amphipathic mean? A molecule that has both hydrophilic and hydrophobic regions 213. State why a phospholipid is amphipathic It has a hydrophobic tail (of mainly C-H bonds) And a hydrophilic phosphate group at the other end of the molecule 214. How do phospholipids arrange Interactions with water cause: themselves when placed in water The hydrophobic tails come together (away from water) The hydrophilic heads to stay in contact with water 215. What structure emerges when Two layers of phospholipids called a phospholipid “bilayer” phospholipids are placed in water That form a sheet-like layer 216. Which molecules will be able to pass Lipids (Hydrophobic molecules) through phospholipid bilayers? Give E.g. steroids like oestradiol and testosterone examples  B1.2 Proteins What is the relationship between amino acid sequence and the diversity in form and function of proteins? How are protein molecules affected by their chemical and physical environments? 217. How many amino acids are coded for in 20 DNA? 218. Draw a generic amino acid 219. What is similar and different Similar: The amino group (NH2), the carboxyl group (COOH) between amino acids? Different: The R group 220. Name the reactions that link two amino Links: Condensation reaction acids & separate them. State the role of Separates: Hydrolysis reaction water in both 221. Explain why condensation reactions To form a bond between molecules, the reaction takes an O from have that name one molecule and OH from another and together they form H2O 222. Explain why hydrolysis reactions have that To break a bond between two molecules a water molecule is split into name H (which binds to one molecule), and OH (which binds to the other). 223. Draw a condensation reaction between two generic amino acids 224. What is the bond called between Peptide bond two amino acids? 225. What is the name for two bonded Two: Dipeptide amino acids, and the name for many Many: Polypeptide bonded amino acids? 226. What is the name for a fully folded and Protein functioning molecule made from many bonded amino acids? 227. State the difference between essential Essential—cannot be synthesised & must be obtained in diet and non essential amino acids Non-essential—can be synthesised from other amino acids 228. Name two conditions that can affect the Temperature overall shape of a protein pH 229. What happens in protein denaturation? The protein loses its typical shape and cannot perform its typical function 230. What is the primary structure of proteins? The sequence of amino acids 231. Name the types of R-groups found amino Hydrophobic acids Hydrophilic—can be polar, or charged (positive or negative) 232. Name the two most common folding Alpha helix configurations of the secondary Beta sheet structure of proteins. 233. What causes the amino acid Hydrogen bonds between the amino acid backbone (not between structure to fold into secondary R-groups) structures? 234. What is the tertiary structure of a The overall folding of the protein protein and what causes it? Caused by the most stable interactions between R-groups 235. Name the two strongest, and two Stronger: Disulphide bond (covalent), Ionic bond weaker interactions between R groups Weaker: Hydrogen bonds, Hydrophobic interactions 236. Which amino acid can participate in Cysteine disulphide bonds? 237. Which amino acid type can participate Charged amino acids in ionic bonding 238. In proteins that are soluble in water Hydrophilic on the exterior where are you most likely to find Hydrophobic in the interior hydrophilic and hydrophobic amino acids? 239. What is the quaternary structure of a A whole protein that is formed from several polypeptides joined together protein? 240. State why hemoglobin represents an Hemoglobin is a protein formed by four polypeptides held example of protein with a quaternary together by non covalent bonds (ionic, and hydrogen bonds) structure 241. State why Collagen represents an Collagen is formed by three polypeptide chains that form a triple helix example of protein with a quaternary structure 242. State why insulin represents an Insulin is formed by two polypeptide chains held together by two disulphide example of protein with a quaternary bonds structure 243. Define conjugated protein and give an A protein with another chemical group attached example E.g. Haemoglobin contains haem with iron  B2.1 Membranes & membrane transport How do molecules of lipid and protein assemble into biological membranes? What determines whether a substance can pass through a biological membrane? 244. With membranes, why is the Cells can separate their contents and conditions from the outside concept of a ‘barrier’ important for a environment living organism? 245. With membranes, why is the concept Cells require a constant flow of energy and matter into and out of them of ‘permeability’ important for a living organism? 246. With membranes, why is the concept Cells can retain their contents & structure inside, while controlling what of being ‘selective’ important for a living enters and what exits organism? 247. State which molecules cannot freely Hydrophilic molecules (e.g. carbohydrates, amino acids, diffuse across phospholipid membranes ions, water) Large molecules (e.g. polymers, vitamin B12) 248. State which molecules can freely diffuse Hydrophobic molecules (e.g. lipids, O2, CO2) across phospholipid membranes 249. In what direction does diffusion Down the concentration gradient across a membrane take place? (From high concentration to low concentration) 250. Which type of proteins enable Channel proteins specific hydrophilic molecules —Called facilitated diffusion diffuse across a membrane? & what type of diffusion is this? 251. Explain the general concept of Channel proteins have hydrophobic molecules on their exterior and facilitated diffusion of hydrophilic a channel formed by hydrophilic amino acids molecules across a membrane —Hydrophilic molecules can move through the channel and across a membrane 252. What type of proteins are able to Protein pumps move hydrophilic molecules against a —Called active transport concentration gradient? & what type of transport is this? 253. Explain the general concept of active Protein pumps use energy from ATP to transport a specific transport molecule over a membrane (allowing selectivity) 254. Name five roles of membrane proteins Membrane transport Enzymes Cell recognition Cell signalling Cell adhesion 255. State the difference between Integral—are embedded in one or both of the integral & peripheral proteins phospholipid layers Peripheral—are attached to the exterior of the membrane 256. State how integral proteins stay Integral proteins have a section of hydrophobic amino acids anchored in a membrane (which position themselves in the centre of the membrane) 257. What is the fluid mosaic model? The currently accepted model for the structure of cell membranes 258. What does the “fluid” bit mean in The parts of a membrane are able to move rapidly laterally in two the “fluid mosaic model”? dimensions 259. What are glycoproteins and glycolipids? Proteins and lipids that have a carbohydrate structure attached 260. Where are glycoproteins and Orientated so that the carbohydrate structure is on the exterior of the glycolipids orientated in membranes? membrane 261. What are the roles glycoproteins and Cell recognition (to other cells) glycolipids located? Cell adhesion (to other surfaces) 262. What is the role of aquaporins They are channel proteins for the facilitated diffusions of water 263. Name the things needed for osmosis Water, Aquaporins in a plasma membrane, with a difference in solute to occur concentration on either side of the membrane 264. In what direction do water molecules From low solute concentration to high solute concentration tend to move over a membrane? 265. Why does the difference in solute The membrane is impermeable to the solutes concentration reach an equilibrium 266. What is the relationship between the The higher the proportion of saturated fatty acids the lower the fluidity proportion of saturated fatty acids in a membrane and the membranes fluidity? 267. What is the function of Regulates the fluidity of the membrane cholesterol in the phospholipid —At high temperatures it stabilises the membrane membrane? —At low temperatures it prevents stiffening 268. Where in the membrane is cholesterol The hydrophobic potion is found embedded in the hydrophobic found? interior The hydrophilic OH group is found on the exterior next to the phosphate heads 269. How do the plasma membranes of Hot—higher proportion of saturated fatty acids (e.g. Thermus bacteria living in cold environments differ to aquaticus) Cold—higher proportion of unsaturated fatty acids those of bacteria living in hot environments? 270. What are vesicles made from? Membrane (phospholipid bilayer) 271. What property of membranes makes Membranes can fuse together and separate easily transport inside vesicles useful? 272. By which process can a cell excrete Exocytosis molecules via vesicles? 273. By which process can a cell ingest Endocytosis molecules into vesicles? 274. State the difference between gated Gated channel proteins are closed and can be opened (allowing and non gated protein channels selectivity) Non-gated channel proteins are always open 275. Give an example of a Acetylcholine receptors open when acetylcholine binds to them neurotransmitter-gated ion channel —allowing Na+ ions to pass into a neuron & continue an action potential 276. Give an example of a voltage-gated ion Sodium voltage-gated channels in neurons open with a change channel & its function in voltage —allowing Na+ ions to pass into a neuron and propagate an action potential 277. Give an example of a protein pump The sodium-potassium pump exchanger & its function Uses ATP to pump 3Na+ over the membrane & 2K+ in the opposite direction —to maintain membrane potential (e.g. in neurons) 278. Give an example cotransporter & its Sodium-dependent glucose cotransporters transport sodium and function glucose across a membrane in the same direction —to transport glucose into cells in the intestine and nephron 279. Explain why cotransporters use e.g. The sodium-dependent glucose cotransporter uses the “indirect” or “secondary” active transport. concentration gradient of sodium to drive the pumping of glucose Use the example of sodium-dependent against its concentration gradient —And in many examples, energy is glucose transporters needed to establish the sodium concentration gradient 280. What are “cell-adhesion molecules” Molecules that connect different cells to each other to form a tissue (CAMs)? B2.2 Organelles & compartmentalisation How are organelles in cells adapted to their functions? What are the advantages of compartmentalization in cells? 281. What are organelles? Discrete subunits of cells that are adapted to perform specific functions 282. Give four examples of organelles Nuclei, vesicles, ribosomes, plasma membrane 283. Give three examples of cellular Cell wall, cytoskeleton, cytoplasm structures that are not considered organelles 284. State the advantage of separating the Post-transcriptional modification can occur before mRNA meets nucleus from the cytoplasm a ribosome (in prokaryotes this can’t happen) 285. State three advantages of Metabolites & enzymes can be concentrated in smaller volumes to compartmentalisation in the cytoplasm increase their rate of reaction Incompatible processes involving different enzymes & metabolites can be separated Potentially harmful (reactive) compounds can be separated from the cytoplasm 286. Give an example of Lysosomes separate hydrolytic enzymes from the rest of the cell compartmentalisation in some Phagocytic vacuoles separate foreign particles & pathogens (that eukaryotic cells the cell has engulfed) from the rest of the cell 287. State the advantage for ATP Double membrane allows separation of the store of H+ ions, and the production of mitochondria having enzymes and substrates of the Krebs cycle in the matrix double membrane 288. State how the double membrane has The inner membrane is folded into cristae to produce a higher evolved to maximize ATP production in surface area for ATP synthase to produce ATP mitochondria 289. State how the intermembrane The intermembrane space has a small volume to concentrate H+ ions space has evolved to maximize ATP production in mitochondria 290. State the advantage for Double membrane allows separation of the store of H+ ions, and the photosynthesis of chloroplasts having enzymes and substrates of the Calvin-Benson cycle in the stroma a double membrane 291. State how the double membrane has Inner membrane, folded to thylakoids to produce a higher surface area evolved to maximize photosynthesis rates for photosystems to absorb light & for ATP synthase to produce ATP 292. State how the thylakoid space has The thylakoid space has a small volume to concentrate H+ ions evolved to maximize photosynthesis rates 293. State two reasons the nucleus is It allows the formation of pores to allow mRNA and proteins to enter formed by a double membrane and leave It allows the nucleus to collapse into vesicles during mitosis and meiosis 294. State the difference between free Free ribosomes—synthesise proteins for work within the cell ribosomes and bound ribosomes of the Bound ribosomes—synthesise proteins that will be transported within rough endoplasmic reticulum the cell to be secreted out of it 295. State the function of the Golgi apparatus Process proteins and packages them into vesicles that will secrete them out of the cell 296. State three functions of vesicles in cells Transport, storage, and digestion 297. What are vesicles formed from? A sphere made from a single membrane 298. What is clathrin and its function? A protein that forms a cage to help shape vesicles as they form (& then releases them) B2.3 Cell specialisation What are the roles of stem cells in multicellular organisms? How are differentiated cells adapted to their specialized functions? 299. What are stem cells? Unspecialised cells that can differentiate into specialised cells 300. Describe the potency of embryonic stem They are totipotent initially but soon become pluripotent cells (can cells differentiate into any cell type except placental cells) 301. Describe the potency of adult stem cells Multipotent stem cells that can differentiate into a few cell types 302. Give two ways that specialised cells are They are fully differentiated and do not produce new cells different to stem cells Specialised cells tend to have short life spans 303. Name the three principal functions of Development & Growth: Produce new tissues adult stem cells Maintenance: Replace dying specialised cells of tissues Reproduction: Produce gametes 304. How can a stem cell produce a Specialised cells turn on only a specific selection of genes in the genome specialised cell if they contain the same genome? 305. Give two examples of stem cell niches Bone marrow & hair follicles in adult humans 306. State the name of stem cells in plants Meristem cells 307. Why do cells typically have a limit on The living volume of the cell needs to exchange with the how big they can be? environment, but there may not be enough surface to carry out the exchanging 308. What does the surface area to The amount of surface that can exchange with the environment volume ratio (SA:V) of an organism And the total living volume of the organism compare? 309. Why does SA:V restrict the As cells get bigger in volume, their metabolic demand increases shape of an organism? Unless they change shape, their won’t be enough surface area to maintain the rate of exchange 310. State the relationship between rate of Rate of exchange ≥ metabolic rate exchange and metabolic rate in organisms 311. What’s the evolutionary consequence of Too little: Slower development, maintenance, and reproduction an organism having too little or too much Too much: Energy is wasted on maintaining the extra exchange surface exchange surface area? 312. What is the equation for calculating SA:V = surface area to volume ratio? 313. What happens to the SA:V ratio of a The SA:V ratio decreases cube as it gets larger, and why? →because the volume increases quicker than the surface area 314. Explain how the cells of the proximal Large surface area: Cells have microvilli tubule are adapted to their function of Short diffusion distance: Thin cells (& only one cell thick till reabsorption capillary) Active transport: Protein pumps & lots of mitochondria to provide ATP 315. How are red blood cells adapted to They have a concave shape (an invagination) that increases its SA:V their role in diffusion 316. State the adaptations of pneumocytes Extreme thinness to allow a short diffusion distance type 1 317. State the adaptations of pneumocytes Contain many secretory vesicles for secreting surfactant onto the type 2 alveolar surface 318. State one adaptation of cardiac muscle The cells are connected through networked branching so that tissue contraction occurs in all directions and efficiently compress the blood 319. Describe two features of muscle fibre Long multinucleate cells (muscle cell) Contain many myofibrils 320. State two hypotheses for why cardiac 1. Convergence—They evolved from different tissues—cardiac muscle muscle fibres are branching & short, which fibres from smooth muscle, and skeletal muscle from other contractile skeletal muscle fibres are not branched cells and long 2. Divergence—They evolved from the same tissues & adapted to different functions—cardiac muscle fibres for rhythmical contraction in all directions, skeletal muscle fibres for more variable work 321. State three adaptations of sperm cells Streamlined shape with little cytoplasm & flagellum for swimming Concentrated mitochondria in the midpiece to power swimming Acrosome contains hydrolytic enzymes to gain entry into the egg cell 322. State the adaptations of human egg cells Very large cytoplasm to provide enough nutrients for development before it reaches the endometrium Cortical granules that change the cell membrane after fertilisation to prevent any other sperms cells from entry 323. State the three principal differences Female eggs—few, large, immobile between male and female gametes Male sperm—many, small, mobile B3.1 Gas exchange How are multicellular organisms adapted to carry out gas exchange? What are the similarities and differences in gas exchange between a flowering plant and a mammal? 324. What is gas exchange and which The obtaining of gases from, and excreting of gases into the organisms do it? environment All organisms 325. State two reasons why becoming a 1. As body size increases—& keeping the same larger organism provides challenges shape—SA:V decreases 2. Many cells are located in the for gas exchange interior, far from the environment 326. State four typical patterns found in gas Permeability—allows gases to pass membranes exchange surfaces in organisms, and Thin tissue layer—increase the rate of diffusion state their function Large surface area—increase the rate of diffusion Moisture—keeps cell membranes intact of the living cells at the surface 327. State how animals can externally Continuously moving fresh air or water over the maintain gas concentration gradients, gas-exchange surface —E.g. ventilation of lungs with air and give two examples —E.g. ventilation of gills with water 328. State two ways for how animals can Developing a dense network of blood capillaries next to the internally maintain gas concentration gas-exchange surface Maintaining a continuous blood flow through the gradients capillaries 329. In what direction do fluids move when From high pressure to low pressure there is a difference in pressure? 330. What is the relationship between An increase in volume causes a decrease in the gas pressure changing the volume of a container and the pressure of a gas inside it? 331. What is the mechanism for inhaling? The diaphragm & external intercostal muscles contract →Volume of lungs increases & air pressure decreases in the lungs →Air moves into the lungs 332. What is the mechanism for exhaling with Internal intercostal muscles & abdominal muscles contract force? →The lungs decrease in volume & air pressure increases in the lungs →Air moves out of the lungs 333. How does exhalation typically occur at Elastic recoil of stretched lung tissue decreases the volume of the lungs rest? 334. What function does the surfactant Reduces the surface tension created by hydrogen bonds between have which covers the alveoli & water molecules —which prevents the alveoli & bronchioles from bronchioles? collapsing 335. State three structural adaptations of the —Branched network of bronchioles to conduct air to mammalian lungs for ventilation & gas extensive alveoli —Extensive network of capillaries exchange surrounds alveoli —Cartilage rings in the trachea & bronchi prevent them collapsing under low pressure 336. Name three adaptations of alveoli Short diffusion distance—Alveolus & capillaries are one cell thick (and capillaries) that allow quick Large surface area—Alveoli are folded into many sacks gas exchange Maintenance of a concentration gradient—Flowing blood in capillaries 337. What does tidal volume mean? The average volume of air inhaled and exhaled (when at rest) 338. What does vital capacity mean? The volume of air breathed out after the deepest inhalation and full exhalation Vital capacity = inspiratory reserve volume + expiratory reserve volume 339. Draw and annotate a diagram of a cross section of a leaf 340. State two ways a typical epidermis is Covered by a waxy cuticle—a barrier to prevent water loss through adapted to for gas exchange evaporation It has stomata (openings) to allow controlled gas exchange 341. What leaf components control the Guard cells, which open or close stomata rate of gas exchange? 342. State the trade off that must be The more stomata are open: negotiated by the opening and closing of —the higher the rate of gas exchange of CO2 and O2, stomata —the higher the rate of water loss 343. What variable typically causes the The rate of water loss from a leaf opening and closing of stomata —If too high, guard cells close stomata 344. Explain how leaves are adapted for Spongy mesophyll cells are located in the middle of the leaf allowing all leaf cells to obtain CO2 for Are not densely packed (have air spaces between) to allow gas diffusion photosynthesis 345. Give two functions of leaf veins Veins contain xylem vessels which: —give structural support —supply water to the leaf to offset water loss through evaporation 346. What is the relationship between the The thinner the leaf, the faster the gas exchange thickness of a leaf and the rate of gas exchange 347. Explain why stomata are often Photosynthesis cannot occur in darkness closed in darkness so no need for diffusion of CO2 and closing the stomata prevents water loss 348. State the relationship between the rate The faster the air movement, the higher the rate of evaporation of water evaporation from leaves and: The higher the air temperature, the higher the rate of air movement, air temperature, air evaporation The less humid the air, the higher the rate humidity of evaporation 349. State three adaptations that have Fewer stomata & smaller leaves—reduced evaporation rate evolved in leaves adapted to dry Succulent leaves or stems—water storage environments Stomata in pits & hairs on leaves—reduced air movement & increased humidity 350. State the adaptations of pneumocytes Extreme thinness to allow a short diffusion distance type 1 351. State the adaptations of pneumocytes Contain many secretory vesicles for secreting surfactant onto the type 2 alveolar surface 352. State why alveolar epithelium Different cell types are present together because different adaptations represents an example of a tissue are required for the overall tissue function 353. How many oxygen molecules can 4 bind to haemoglobin in total? 354. When oxygen binds to a haem group A conformational change in the protein what does it cause? —which increases the affinity of the other haem groups for oxygen (called cooperative binding) 355. When oxygen unbinds from a haem A conformational change in the protein group what does it cause? —which decreases the affinity of the other haem groups for oxygen (called cooperative binding) 356. Explain how cooperative binding of The binding of one oxygen molecule can increase the rate of binding oxygen to haem groups is beneficial three more when in pulmonary capillaries The dissociation of one oxygen molecule can increase the rate of the other three dissociating when in systemic capillaries 357. How does carbon dioxide bind to It binds to the protein (not the haem group) to form haemoglobin? carbaminohaemoglobin 358. What does the binding of carbon A conformational change in the protein dioxide to haemoglobin cause? —which decreases the affinity of the haem groups for oxygen 359. Explain how the production of The more carbon dioxide there is the higher the need for carbaminohaemoglobin is beneficial oxygen (higher respiratory demand) The more carbon dioxide there is the more likely oxygen will dissociate from haemoglobin 360. Why does a graph of—oxygen Cooperative binding means that when an oxygen molecule binds or concentration & average number of O2 dissociates, it changes the chances of the other haem groups binding molecules per or dissociating oxygen haemoglobin—produce an S-shape curve, instead of a line 361. What is the benefit of cooperative It makes haemoglobin more sensitive to oxygen concentration binding in haemoglobin? —allowing it to quickly bind many oxygen molecules in the lungs, and offload them in areas that need them 362. Why does a graph of—oxygen It shows that the binding of carbon dioxide to haemoglobin causes a concentration & average number of O2 decrease in affinity for oxygen molecules per haemoglobin—show and S curve that shifts to the right in the presence of CO2 363. Why does fetal haemoglobin have Fetal haemoglobin must be able to take oxygen from the mother’s blood a higher affinity for oxygen than adult haemoglobin? B3.2 Transport What adaptations facilitate transport of fluids in animals and plants? What are the differences and similarities between transport in animals and plants? 364. State the function of arteries, Arteries: carry blood away from the heart under pressure capillaries, and veins Capillaries: exchange substances with cells Veins: carry blood back to the heart under low pressure 365. State four adaptations of capillaries —Extensive branching —High surface area compared to the volume of the lumen (narrow diameter) —Thin walls (one cell thick—the cells differentiate to be extremely thin) —Fenestrations (gaps between cells) in capillaries where diffusion has to be rapid 366. State an adaptation of arteries Thick walls composed of muscle and elastic tissue to withstand high pressure 367. State two adaptations of veins —Valves to prevent backflow of blood (making flow unidirectional) —Thin flexible walls—allows compression by muscles (maintaining flow) 368. What causes coronary heart disease, Cause: A blockage in the coronary arteries (that transport and what is the mechanism for the oxygenated blood to heart tissues) symptoms of the disease? →which causes Less oxygen & glucose to be transported to heart muscle tissue →which causes Low rate of cell respiration & ATP production →which causes Heart tissue death (and heart may stop beating) →which causes Lower oxygen & glucose flow to the body tissues 369. How are xylem vessels formed? Xylem cells grow to produce the vessel They carry out programmed cell death to leave the cell wall & an empty lumen 370. Name the two principal components of Cellulose & Lignin xylem 371. State four adaptations of xylem for its —Lack of cell contents (just the cell wall as a tube) role in water transport —End walls are absent (or incomplete) to allow unimpeded flow between cells —Pits allow entry and exit from the xylem —Lignin in cell walls to prevent collapse under negative pressure 372. Describe the two types of xylem vessels Tracheid—thinner, less efficient (in all vascular plants) Vessel element—wider, more efficient (mainly in angiosperms) 373. What is the overall consequence of Water is pulled by negative pressure evaporating water from leaf cell walls →and water flows from roots to leaves on the water in the plant? 374. State the difference between Adhesion: water molecules attracted to other molecules due adhesion & cohesion of water to H-bonds Cohesion: water molecules attracted to each other due to H-bonds 375. Explain the process that initiates the Adhesion of water to leaf cell walls process of transpiration in the leaf →Energy from the environment causes water evaporation from leaf cell walls →The space left creates tension between water molecules →The tension draws water towards leaf cell walls 376. Explain the mechanism of (After water evaporates from cell walls) transpiration flow through xylem →Negative pressure pulls water molecules through xylem towards leaves →Cohesion causes water molecules to form a continuous chain of connected molecules that doesn’t break →which causes continuous flow 377. Explain how transpiration Transpiration functions by negative pressure causes the requirement of lignin in →air pressure (positive) pushes on the xylem tissue xylem →lignin prevents the xylem vessels from collapsing 378. Describe the structural difference Bony fish—have a single circuit that passes to the gills first and then between the circulatory system circuits directly to the body tissues found in bony fish and mammals Mammals—have a double circuit that passes to the lungs first, then back to the heart to be pumped again to the body tissues 379. State the advantage of a circulatory A higher blood pressure can be maintained system with a double circuit (compared to a —which maintains higher blood velocity and filtering of plasma contents single circuit) 380. How are red blood cells adapted to They have a concave shape (an invagination) that increases its SA:V their role in diffusion 381. State the difference between the Tissue fluid contains the contents that diffuse out of plasma (water, composition of tissue fluid & plasma ions, glucose, amino acids, hormones, etc) Plasma contains similar contents as tissue fluid except for what cannot diffuse out of capillaries (red blood cells, large proteins) 382. Explain the input that form tissue fluid Blood pressure in the capillary causes plasma to leave the capillary (but filtering larger contents) 383. Explain the two outputs that drain tissue Lower pressure at the venule end of capillaries allows tissue fluid to fluid drain back into capillaries (due to osmosis) Excess fluid drains into the lymphatic system 384. State two adaptations of lymph ducts Valves to prevent back flow that allows them to collect and transport Thin walls with gaps to allow entry of fluid tissue fluid to the heart 385. Draw and label the heart 386. Name the function of the atria Pump blood into the ventricles 387. Why does the left ventricle have thicker More pressure is required to pump blood around the muscle tissue than the right ventricle? systemic circuit Less pressure is required to pump blood around the pulmonary circuit 388. Name the function of the heart valves Prevent backflow of blood (into areas of lower pressure) 389. What is the function of the septum? Separate deoxygenated blood from oxygenated blood Separate the two ventricles which generate different blood pressures 390. State two reasons why the heart The blood in the right side is deoxygenated & high in CO2 requires its own coronary arteries & Diffusion distance is too large from the centre of a chamber to the majority capillaries, instead of making use of the of cells blood in its chambers 391. State one adaptation of cardiac muscle The cells are connected through networked branching so that tissue contraction occurs in all directions and efficiently compress the blood 392. What is the mechanism of the cardiac The pacemaker generates an action potential (electrical impulse) cycle for the left side of the heart →Muscle in left atrium contracts causing an increase in pressure that pushes blood into the left ventricle →The action potential continues onwards to the left ventricle →Muscle in left ventricle contracts causing an increase in blood pressure →which causes blood to move into the aorta under pressure 393. What is the difference between Diastolic pressure—arterial blood pressure at its lowest (between diastolic & systolic blood contractions) Systolic pressure—arterial blood pressure at its highest pressure? (during the contraction of the ventricles) 394. In what direction are products of From sources to sinks photosynthesis transported 395. What is the difference between sources & Sink—A part of a plant with a net consumption or storage sinks of sucrose Source—A part of a plant with a net production of sucrose 396. Give two examples of sinks and sources Sinks: Flower, roots, growing leaf, fruit Sources: Mature leaf, tubers 397. Explain why nutrients move from The lowest water potential is in phloem near sources sources to sinks in phloem in the →causing water to enter sieve tube elements process of translocation →causing high turgor pressure & movement of phloem sap towards lower pressure 398. What is the name of the cell that Sieve tube elements forms the vessel of phloem and what do Sieve tube elements together form a sieve tube they form? 399. Describe the structure of sieve tube They have porous sieve plates at their ends elements They have no nuclei and few organelles to allow for better flow 400. What is a companion cell and its A cell that is found next to sieve tube elements and carries out the life function? processes for the sieve element (production of ATP, proteins, etc) 401. State two adaptations of companion Many mitochondria cells that allow them to carry out their They have channels (called plasmodesmata) that connect them to function sieve tube elements 402. How can root pressure be created by By transporting ions into the root plants? →which causes a low water potential and in the entry of more water 403. State a function of root pressure Help with creating movement of water through xylem when transpiration rates are low (e.g. in very high humidity, when there are insufficient leaves) B3.3 Muscle & motility How do muscles contract and cause movement? What are the benefits to animals of having muscle tissue? 404. State four reasons for locomotion in Foraging for food, Escaping danger, Searching for mates, Migration organisms 405. Give an example of rapid movement Venus flytraps use electrical signals to close a trap which in plant species captures insects Mimosa pudica uses electrical signals to fold its leaves when touched 406. Give an example of movement in a Sea anemones can snare & pull in prey using their tentacles sessile animal 407. State three ways that marine Limbs have evolved to form flippers mammals have evolved for locomotion in Bodies have evolved to be streamlined water Airways in cetaceans have evolved to develop a blowhole at the top of the head 408. How are the tails of marine mammals Mammals—tails form a fluke with horizontal fins & performs up-down different to those of fish movements Fish—tails have vertical fins & perform side-to-side movements 409. Describe two features of muscle fibre Long multinucleate cells (muscle cell) Contain many myofibrils 410. State two hypotheses for why cardiac 1. Convergence—They evolved from different tissues—cardiac muscle muscle fibres are branching & short, which fibres from smooth muscle, and skeletal muscle from other contractile skeletal muscle fibres are not branched cells and long 2. Divergence—They evolved from the same tissues & adapted to different functions—cardiac muscle fibres for rhythmical contraction in all directions, skeletal muscle fibres for more variable work 411. Name the components of the motor unit Motor neuron Neuromuscular junction (type of synapse) All the muscle fibres that the motor neuron stimulates 412. What is the difference between a Larger motor units have more muscle fibres (for the single motor neuron) larger and smaller motor unit 413. What is the relationship between the Large motor units tend to exist in muscles that produce large powerful size of a motor unit and its function movements (e.g. leg muscles) Small motor units tend to exist in muscles that require fine control (e.g. eye muscles) 414. What determines the strength of a The total number of motor units recruited muscle contraction? 415. What is the function of the Provide a framework for the attachment of muscles and to act as skeleton in movement? levers for the muscles to pull on 416. State two general differences Vertebrates—have an endoskeleton & muscles attach to the exterior between vertebrate & arthropod of bones Arthropods—have an exoskeleton & muscles attach to the muscular-skeletal interior of the skeleton systems 417. What is the reason for muscles Muscles can only contract in one direction working in antagonistic pairs? So, another muscle is needed to contract in the opposite direction 418. Give an example of antagonistic Internal intercostal muscles move the ribcage downwards pairs & their function External intercostal muscles raise the ribcage 419. State how external & internal When one antagonistic muscle contracts it stretches the other intercostal muscles work →which causes potential energy to be stored in the stretched protein synergistically titin (in the sarcomere) 420. Describe the function of a joint A connection between bones that allows movement 421. What is the function of cartilage in a joint? Reduce friction and absorb compression forces 422. What is the function of synovial fluid? Lubrication between bones Provides nutrients to the cartilage 423. What is the function of a tendon? Attach muscle to bone 424. What is the function of a ligament? Attach bone to bone 425. Name the two bones that connect at Pelvis & femur the hip joint 426. Describe the functional unit of Sarcomere muscle and where it is located Found as repeating units (called myofibril) 427. How does a sarcomere become Myosin and actin slide over each other shorter during contraction? (The fibres do not shorten) 428. Explain the principal molecular Myosin heads bind to actin binding sites cause of sarcomere contraction → which causes myosin heads to change shape and ‘pull’ on the actin → which causes actin filaments to be pulled towards the centre of the sarcomere 429. What is the function of ATP in Releases the myosin head from the actin filament muscle contraction? 430. State two functions of titin in muscle Helps sarcomeres recoil after stretching contraction Prevent overstretching 431. Draw a sarcomere including the z line, myosin, actin, and titin 432. Explain the mechanism of the Release of calcium ions from sarcoplasmic reticulum stimulation of a muscle contraction by an →calcium ions bind to troponin action potential → which causes tropomyosin to move & expose binding sites → which allows myosin heads to bind to actin and cause