Biology Est. PDF

definition subtopics questions keyword REPRODUCTION IN PLANT Parts of insect pollinated flower: Sepals: 5 green sepals Petals: 5 brightly colored petals to attract insects of different size and shapes Standard petal: deep blue standard petal has lines to guide insects where the nectar is. The line...

definition subtopics questions keyword REPRODUCTION IN PLANT Parts of insect pollinated flower: Sepals: 5 green sepals Petals: 5 brightly colored petals to attract insects of different size and shapes Standard petal: deep blue standard petal has lines to guide insects where the nectar is. The lines are called nectar guides Wing petals: enclosed by standard petal Keel petals: enclosed by wing petals and encloses reproductive organs Stamens: 10 stamens, 9 to form a trough that encloses carpel, while the last stamen is free Carpel: contains stigma, style, ovary: (contains single row of ovules) Factors affecting germination: - Oxygen: needed for aerobic respiration to release energy, used for cell division, growth and synthesis of proteins and enzymes - Suitable temperature: chemical reactions will occur - enzymes work best at optimum temperatures. Example, glucose breaks down during respiration to release energy. - Water: for digestion, solvent for transport of digested products Process: When conditions are right, a seed absorbs water and oxygen, causing it to expand. The seed coat splits, allowing the root to come out along with the shoot, then develops into leaves and stems. Then the sunlight warms the soil and is essential for germination. Once the leaves appear, the plant begins photosynthesis for energy. Inside the seed, the embryonic plant includes a root, stem, and leaves, with a nutrient-rich endosperm. Cotyledons provide nourishment until the plant can photosynthesize on its own. REPRODUCTION IN HUMAN Reproduction organ in male: Testis: produces sperm, and sex hormones such as testosterone Scrotum: low temperature for sperm to develop properly Sperm duct: to let sperm travel coming from testis Prostate gland: produces fluid (semen) that mix with the sperm to nourish it and stimulate them to swim actively Urethra: passes out semen and urine out of the body Penis: enters vagina to deposit semen containing sperm Sperm: male gamete, produces a lot when male => physically mature Parts of sperm: Head: 2.5 μm wide, contains large nucleus, carries haploid set of chromosomes, has acrosome containing enzymes that breaks down egg membranes. Middle piece: contains mitochondria that provides energy for sperm to swim towards the egg. Tail: enables sperm that can move itself to swim towards the egg (flagellum) Sperm move from testis -> sperm duct -> urethra -> outside Reproduction organ in female: Ovary: produces eggs and hormones such as oestrogen and progesterone Oviduct/fallopian tube: leads ovary to uterus and makes it easier for egg to enter oviduct with the help of cilia. Egg = fertilized Uterus: where the fetus develops during pregnancy and pushes the fetus out during birth. Endometrium: lining of uterus, where embryo implants Cervix: joins vagina and allows menstrual blood to flow during menstruation Vagina: leads from cervix to outside, semen deposited during mating Ovum: female gamete Organs involved during pregnancy: - Endometrium/uterine lining & fetal blood capillaries } placenta - Oviduct - Cervix INHERITANCE DNA & mRNA transcription: DNA = A+T, C+G mRNA = A+U, A+T, C+G Homologous chromosome: pair of chromosomes with same shape, genes and sequence Alleles: different forms of same gene Dominant allele: allele that’s expressed Recessive allele: allele that’s not expressed Heterozygous: different alleles Homozygous: identical alleles: - Homozygous dominant: 2 dominant alleles - Homozygous recessive: 2 recessive alleles Blood group crossing: Blood group Genotype A IA IA / IA IO B IB IB / IB IO AB IA IB O IO IO Hemophilia crossing: Male Allele Female Allele Normal male XY Normal female XX Hemophilia male Xh Y Hemophilia female Xh Xh Carrier male - Carrier female Xh X BIOTECHNOLOGY Biotechnology: use of living systems/organisms to develop products for mankind benefits. Used to produce enough food for population demands, varieties of crops and livestock, and pharmaceuticals for disease treatment. Anaerobic: absence of oxygen, in yeast equation = glucose -> ethanol + CO2 (+small energy) Aerobic: presence of oxygen, equation = glucose + oxygen -> CO2 + water (+large energy) Q: How is pectinase used? Pectinase breaks down pectin, causing the cells to separate and fruit becoming soft. Suspended solids from polysaccharides (pectin, cellulose and starch) making juice cloudy. Pectinase, amylase and cellulose are added to break down polysaccharides to sugars. Pectinase: enzyme produced during fruit ripening consisting of polysaccharides, used for juice making. Lactase: a sugar found in milk, breaks down lactose to simple sugars (glucose and galactose), producing lactose free milk. Lipase: as an enzyme for biological washing powders, breaks down fats to fatty acids and glycerol. Protease: as an enzyme for biological washing powders, breaks down proteins to amino acids. Production of penicillin: 1) The air sparger pumps sterile air into the fermenter as tiny bubbles to dissolve oxygen in the nutrient fluid for aerobic respiration. 2) Stirring paddles mixes microorganisms with air bubbles and nutrient fluid, preventing them from sinking. 3) Cooling system consists of a water jacket that circulates cooling water around the fermenter to remove excess heat from aerobic respiration, maintaining optimal temperatures. 4) Acid or alkali is added to maintain the optimum pH for enzymes and microorganisms. 5) Exhaust pipe allows waste products, such as CO2, to escape from the fermenter. 6) Monitoring probes measure temperature, pH, and nutrient levels to ensure they remain at optimal values. Restriction enzymes: cuts DNA and produces sticky ends Complementary base pairing: bacterial and human DNA combined Ligase: seals sticky ends, inserts human DNA in bacterial plasmid Recombinant DNA: consists of bacterial and human DNA (2 different organisms) Process genetic engineering: 1. Extract DNA in the human chromosome containing insulin by using restriction enzymes to cut and produce sticky ends. 2. Obtain plasmid from a bacterium, cut with restriction enzyme. 3. Mix plasmid and DNA with human insulin gene, paired by complementary bases with sticky ends. 4. Mix recombinant plasmid with bacterium E.coli, apply heat/small shock that opens pores in the cell membrane of the bacterium for plasmid to enter. 5. The bacterium acquires a foreign gene called transgenic bacterium, used for insulin. Bacterium can be placed in the fermenter. Advantages of genetic engineering: Insulin to treat patients: - Cheap and easy to produce large quantities of insulin - No risk of contamination by bacteria - Insulin is identical to human insulin, no allergies induced Crops genetically modified: - Resistant to pests and herbicides (glyphosate) - Reduces environmental pollution - Improved nutritional quality Disadvantages of genetic engineering: - Production of superweeds through cross pollination - Kills useful insects causing loss of biodiversity - Allergic risks Yogurt making: First, heat milk to about 82°C to denature proteins creating a smooth texture and killing unwanted bacteria. Then, let the milk cool to around 30°C, the optimal temperature for the starter cultures to thrive. Add the starter yogurt (1-2 tablespoons). Put in a container, cover, and keep warm for 4-12 hours to allow fermentation. Lastly, refrigerate it. What affects the yogurt result: - Temperature: affects acidity and carbonation rate, temperature = low and not too high VARIATION & SELECTION Variation: differences in traits between individuals of the same species Continuous variation: affected by environment, additive effect of genes Discontinuous variation: easily distinguishable, not affected by environment Mutation: sudden change in structure of a gene/in a chromosome number Gene mutation: sudden change in the base sequence in the DNA Mutation results: - new alleles - genetically different offspring - has phenotypes allowing them to survive & reproduce Mutagens: certain agents in the environment with greatly increased exposure Random mating: different varieties of the same species produce more variations in the offspring Genetic variation: has advantages and disadvantages, organisms with alleles resistant to diseases/camouflage may survive, but others die. Organisms with those alleles will pass on to offspring. Adaptive features: inherit features to survive and reproduce (Xerophytes and Hydrophytes) Xerophytes: survive in desert - Needle like leaves to reduce surface area & rate of respiration - Thick waxy cuticle that reduces water loss by evaporation - Sunken stomata, which water vapor accumulates in depressions out of stomata - Hair trapping water vapor that diffuses out of the stomata, reduces diffusion of water vapor and reduces rate of transpiration Disadvantage - Less CO2 enters plant Advantage - Less oxygen lost - Less water lost Hydrophytes: survive in water - Absence of cuticle and stomata, gas exchange through the whole surface of the leaves - Large air chambers in leaf to reduce density of leaves, still get light to photosynthesise - Stomata in the upper epidermis for gas exchange, helps obtain CO2 for photosynthesis - Concentration of dissolved carbon dioxide is lower than atmospheric carbon dioxide - Doesn't require xylem vessels, and offer little resistance to water flow Natural selection: varieties open to diseases/environmental changes may die Evolution: involving a series of genetic variations from original to new species Adaptation: organisms develop and inherit adaptive features through natural selection Q: How does natural selection lead to development of antibiotic resistant bacteria? Over/under exposure to antibiotics develops mutations in their genes that allows them to survive. Q: If a patient with bacterial infection is treated with antibiotics, but some bacteria survive, how? The bacteria that survived underwent the process of natural selection. Selective breeding: producing improved breeds of plants/animats Selection: producing plants and animals with traits Breeding soya bean (SB in plants): Breeders analyze seeds from different plants and select the high oil content seed for oil production. After generations, pure-bred plants that produce seeds with desired qualities are obtained. Then, plants can be self propagated. to ensure the desirable genes are inherited. Artificial vs Natural selection Artificial Natural Selection by humans Selection by environmental conditions Selected features for human’s benefit Selected features for organism’s benefit Genetic variation decreases Genetic variation increases Faster process Slower process