Biology Chapter 5: Species and Diversity
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Questions and Answers

What is the primary criterion for defining a biological species?

  • Organisms have identical genetic material
  • Organisms share the same habitat
  • Organisms can interbreed and produce fertile offspring (correct)
  • Organisms exhibit similar physical characteristics

Which of the following best describes the concept of genetic diversity?

  • Relationships between different species
  • Variations of genes within a species (correct)
  • The total number of species in a given area
  • Environmental factors affecting ecosystems

According to Darwin’s Theory of Evolution, what determines which organisms survive and reproduce?

  • The traits best suited to their environment (correct)
  • Random chance without any influencing factors
  • The size of the organisms in the population
  • The number of offspring produced

What type of diversity encompasses the variety of biological communities in ecosystems?

<p>Ecological diversity (C)</p> Signup and view all the answers

What is an example of a hybrid organism?

<p>Zorse (D)</p> Signup and view all the answers

What occurs during the S phase of the cell cycle?

<p>DNA is synthesized and replicated (C)</p> Signup and view all the answers

What is the primary function of mitosis?

<p>To ensure genetic continuity (C)</p> Signup and view all the answers

Which phase is characterized by the chromosomes aligning at the metaphase plate?

<p>Metaphase (C)</p> Signup and view all the answers

How long do human somatic cells typically undergo mitosis?

<p>0.5 - 1.5 hours (C)</p> Signup and view all the answers

Which of the following events occurs during anaphase?

<p>Chromatids are pulled to opposite ends of the cell (C)</p> Signup and view all the answers

What does cytokinesis refer to?

<p>The division of the cytoplasm (C)</p> Signup and view all the answers

What characterizes the G1 phase of the cell cycle?

<p>Cells grow and mature after division (A)</p> Signup and view all the answers

What happens during programmed cell death, known as apoptosis?

<p>Cells cease to divide and die systematically (C)</p> Signup and view all the answers

What is the significance of similarities in chemical compounds found in cells?

<p>They provide evidence of phylogenetic relationships. (C)</p> Signup and view all the answers

How do shared derived characters contribute to understanding evolutionary relationships?

<p>They indicate evolutionary innovations unique to a specific group. (C)</p> Signup and view all the answers

Which of the following represents a group of organisms with a common ancestor?

<p>Clade (C)</p> Signup and view all the answers

What does a cladogram illustrate?

<p>The evolutionary relationships among a group of organisms. (D)</p> Signup and view all the answers

Which process describes changes in classification systems over the years?

<p>Evolution (A)</p> Signup and view all the answers

Why might two organisms that look dissimilar still be related?

<p>They possess similar genes in their DNA. (D)</p> Signup and view all the answers

The amnion is a significant feature in the embryonic development of which group?

<p>Reptiles, birds, and mammals (C)</p> Signup and view all the answers

What is an 'Out-Group' in the context of cladogram construction?

<p>An organism that is only distantly related and used for comparison. (D)</p> Signup and view all the answers

Which kingdom includes organisms such as yeasts and molds?

<p>Fungi (A)</p> Signup and view all the answers

What type of cell structure characterizes organisms in the domain Bacteria?

<p>Prokaryotic with thick and rigid cell walls (A)</p> Signup and view all the answers

What characteristic distinguishes Archaebacteria from other bacterial domains?

<p>Cell walls do not contain peptidoglycans (C)</p> Signup and view all the answers

Which of the following groups is primarily unicellular?

<p>Protista (C)</p> Signup and view all the answers

How do fungi obtain nutrients?

<p>By absorption after breaking down organic matter (C)</p> Signup and view all the answers

Which statement about Animalia is true?

<p>Animalia are multicellular without a cell wall (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of life?

<p>Complex structure (D)</p> Signup and view all the answers

Which type of virus is known for infecting bacteria?

<p>Bacteriophage (C)</p> Signup and view all the answers

Which characteristic is shared between viruses and living organisms?

<p>Contain genetic material (D)</p> Signup and view all the answers

What is a common characteristic of viruses?

<p>Must rely on host cells to reproduce (A)</p> Signup and view all the answers

Which of the following does NOT fully support the classification of living organisms?

<p>Presence of photosynthetic ability (B)</p> Signup and view all the answers

What is an example of a geographical barrier impacting species interaction?

<p>Distinct habitats separated by mountains (A)</p> Signup and view all the answers

What is the primary purpose of taxonomy in biology?

<p>To classify organisms and assign them a name. (C)</p> Signup and view all the answers

Which of the following correctly orders the levels of classification from broadest to most specific?

<p>Domain, Kingdom, Phylum, Class, Order, Family, Species (A)</p> Signup and view all the answers

What characteristic distinguishes homologous structures from analogous structures?

<p>Homologous structures are derived from a common ancestor. (D)</p> Signup and view all the answers

Which system did Carolus Linnaeus create for naming organisms?

<p>Binomial Nomenclature (A)</p> Signup and view all the answers

Why was Linnaeus' classification system revised over time?

<p>It was too simplistic and did not show evolutionary relationships. (C)</p> Signup and view all the answers

Which of the following is considered the most specific level of classification?

<p>Species (D)</p> Signup and view all the answers

What does phylogeny refer to in modern taxonomy?

<p>The evolutionary history of an organism. (B)</p> Signup and view all the answers

Which of the following is NOT a rule of Binomial Nomenclature?

<p>The genus name is always written in lowercase. (B)</p> Signup and view all the answers

What type of structures do whales' hip bones exemplify?

<p>Vestigial Structures (C)</p> Signup and view all the answers

Which of the following pairs play a significant role in the classification of organisms today, beyond just morphology?

<p>Genetic and biochemical similarities (A)</p> Signup and view all the answers

What happens to the number of chromatids after the S phase during cell division?

<p>They double to 2 per chromosome. (A)</p> Signup and view all the answers

What role do telomeres serve at the ends of chromosomes?

<p>They form protective caps to prevent DNA loss. (C)</p> Signup and view all the answers

Which of the following describes spontaneous mutations?

<p>They result from natural processes in the cell. (C)</p> Signup and view all the answers

What is the outcome of meiosis?

<p>It produces four haploid gametes. (A)</p> Signup and view all the answers

What distinguishes haploid cells from diploid cells?

<p>Haploid cells have one copy of each chromosome. (C)</p> Signup and view all the answers

Which of the following correctly describes homologous chromosomes?

<p>They contain the same genes but may have different alleles. (D)</p> Signup and view all the answers

What is a key characteristic of a mutation?

<p>Mutations can lead to changes in DNA structure. (C)</p> Signup and view all the answers

During which phase do homologous chromosomes separate?

<p>Anaphase II of meiosis. (D)</p> Signup and view all the answers

What is the result of fertilization?

<p>Restoration of diploid status. (C)</p> Signup and view all the answers

What is one key difference between the lytic cycle and the lysogenic cycle of viral replication?

<p>The lysogenic cycle keeps the host cell intact. (A)</p> Signup and view all the answers

In the lytic cycle, what is the order of the steps followed from virus attachment to host cell destruction?

<p>Attachment, Synthesis, Assembly, Release (A)</p> Signup and view all the answers

What occurs during lysogeny when the viral DNA is integrated into the host's genome?

<p>The host cell replicates the viral DNA. (C)</p> Signup and view all the answers

Which statement about DNA structure is true?

<p>DNA is organized into double-stranded helical shapes. (B)</p> Signup and view all the answers

Which of the following is a characteristic of eukaryotic chromosomes during cell division?

<p>Chromosomes are packaged with proteins called histones. (A)</p> Signup and view all the answers

Which nitrogenous base pairs with adenine in DNA?

<p>Thymine (A)</p> Signup and view all the answers

What process involves the conversion of DNA into RNA?

<p>Transcription (C)</p> Signup and view all the answers

During which phase of the cell cycle does DNA replication occur?

<p>Interphase (C)</p> Signup and view all the answers

What is the basic unit of DNA that consists of a sugar, phosphate group, and nitrogenous base?

<p>Nucleotide (A)</p> Signup and view all the answers

How many total chromosomes are found in a human cell?

<p>46 (B)</p> Signup and view all the answers

In the context of DNA, what do the letters A, T, C, and G represent?

<p>Nitrogenous bases (C)</p> Signup and view all the answers

What is the primary role of proteins synthesized from genes?

<p>They are responsible for traits in organisms. (B)</p> Signup and view all the answers

Which virus is an example of one that utilizes the lysogenic cycle?

<p>Herpes virus (B)</p> Signup and view all the answers

The location of a gene within a chromosome is referred to as what?

<p>Locus (B)</p> Signup and view all the answers

What hypothesis proposed by James Hutton emphasizes that geological processes occur slowly over millions of years?

<p>Gradualism (C)</p> Signup and view all the answers

Which scientist is known for developing the concept of uniformitarianism?

<p>Charles Lyell (C)</p> Signup and view all the answers

What did Georges Cuvier's research on fossils lead him to discover about older strata?

<p>They host fossils that are increasingly different from living species. (C)</p> Signup and view all the answers

Which principle describes the idea that past geological events occurred suddenly and through mechanisms different from those operating today?

<p>Catastrophism (A)</p> Signup and view all the answers

What was the primary idea of Jean-Baptiste Lamarck’s theory?

<p>Organisms gain characteristics during their lifetime and pass them on. (D)</p> Signup and view all the answers

What observation did Thomas Malthus make that influenced Darwin's theories?

<p>Human population grows faster than the death rate. (C)</p> Signup and view all the answers

What does the hypothesis termed 'Theory of Acquired Characteristics' suggest?

<p>Traits acquired in life can be inherited by offspring. (A)</p> Signup and view all the answers

What was one of the implications of Darwin having a copy of Lyell’s book?

<p>He recognized the Earth must be old for life to change. (B)</p> Signup and view all the answers

What aspect did Cuvier's work on catastrophism highlight about extinct species?

<p>Catastrophic events were solely responsible for their extinction. (B)</p> Signup and view all the answers

What did the study of rock strata help scientists conclude about the age of the Earth?

<p>The Earth is very old and changes occurred slowly over time. (D)</p> Signup and view all the answers

What is the principle of segregation regarding alleles during meiosis?

<p>A pair of alleles segregate so that only one allele is present in each gamete. (D)</p> Signup and view all the answers

In a dihybrid cross between two heterozygous individuals (TtPp x TtPp), what is the expected phenotypic ratio?

<p>9:3:3:1 (B)</p> Signup and view all the answers

What describes incomplete dominance in hybrid offspring?

<p>The hybrid displays a blended phenotype. (C)</p> Signup and view all the answers

Which of the following traits is an example of codominance?

<p>Black cow x White cow = Spotted cow. (B)</p> Signup and view all the answers

Which statement best describes polygenic traits?

<p>They are influenced by multiple genes leading to a range of phenotypes. (A)</p> Signup and view all the answers

Why are sex-linked recessive traits more common in XY genotypes than in XX genotypes?

<p>XY genotypes have only one X chromosome, creating a risk for expression. (B)</p> Signup and view all the answers

What best describes the scientific theory of evolution?

<p>An explanation supported by extensive evidence based on observations and experimentation. (D)</p> Signup and view all the answers

What is a common misconception about dominant and recessive traits?

<p>Dominant traits are always more common in a population. (C)</p> Signup and view all the answers

What role does the X chromosome play in sex-linked traits?

<p>It carries a majority of sex-linked traits due to its larger size. (A)</p> Signup and view all the answers

What is meant by evolutionary theory?

<p>A comprehensive explanation of the diversity of life, based on evidence. (C)</p> Signup and view all the answers

What is the main mechanism by which Darwin proposed evolution occurs?

<p>Natural selection (A)</p> Signup and view all the answers

How did Darwin's observations of finches in the Galapagos Islands contribute to his theory?

<p>They provided evidence for a common ancestor. (D)</p> Signup and view all the answers

Which of the following statements best reflects what Darwin meant by 'fitness' in the context of natural selection?

<p>It describes an individual's reproductive success in a specific environment. (C)</p> Signup and view all the answers

What does the phrase 'Survival of the Fittest' imply about evolution?

<p>Adaptations suitable to the environment enhance survival and reproduction. (C)</p> Signup and view all the answers

Which of the following is NOT a concept related to Darwin’s theory of natural selection?

<p>Inheritance of acquired characteristics (A)</p> Signup and view all the answers

What role does artificial selection play in understanding Darwin's theory?

<p>It illustrates how humans can selectively breed organisms for desirable traits. (B)</p> Signup and view all the answers

Why was Darwin reluctant to publish his findings initially?

<p>He challenged deeply held scientific and religious beliefs. (A)</p> Signup and view all the answers

In the context of Darwin's theory, what is 'descent with modification' primarily associated with?

<p>The process through which species evolve and diversify from common ancestors. (C)</p> Signup and view all the answers

What is a critical aspect of the struggle for existence in Darwin's theory?

<p>Members of a species compete for limited resources. (B)</p> Signup and view all the answers

How does natural selection influence the characteristics of a population over time?

<p>It amplifies favorable inherited traits and diminishes less favorable ones. (C)</p> Signup and view all the answers

What is the primary purpose of crossing over during meiosis?

<p>To increase genetic diversity (C)</p> Signup and view all the answers

During which phase of meiosis do homologous chromosomes first pair up and exchange genetic material?

<p>Prophase 1 (B)</p> Signup and view all the answers

What characterizes the daughter cells produced at the end of meiosis?

<p>They are haploid with one copy of each chromosome (C)</p> Signup and view all the answers

Which of the following accurately describes a significant difference between spermatogenesis and oogenesis?

<p>Oogenesis typically results in one functional gamete and polar bodies. (B)</p> Signup and view all the answers

What is the main outcome of nondisjunction during meiosis?

<p>Produces gametes with abnormal chromosome number (C)</p> Signup and view all the answers

What phase follows metaphase 1 in meiosis?

<p>Anaphase 1 (A)</p> Signup and view all the answers

Which chromosomal abnormality is characterized by the presence of only one chromosome from a homologous pair?

<p>Monosomy (A)</p> Signup and view all the answers

Why does meiosis not include a second round of DNA replication before meiosis 2?

<p>It allows for the reduction of chromosome number. (A)</p> Signup and view all the answers

Which of the following genetic tests provides definitive diagnosis for chromosomal abnormalities?

<p>Amniocentesis (D)</p> Signup and view all the answers

Which statement best describes the significance of independent assortment during meiosis?

<p>It results in unique chromosome combinations in gametes. (C)</p> Signup and view all the answers

What is the likely outcome of a gamete produced after nondisjunction in meiosis II?

<p>The gamete will have an extra chromosome (A), The gamete will have a missing chromosome (D)</p> Signup and view all the answers

What occurs during anaphase 1 of meiosis?

<p>Homologous chromosomes are pulled apart. (A)</p> Signup and view all the answers

Which syndrome is most commonly associated with Trisomy 21?

<p>Down Syndrome (B)</p> Signup and view all the answers

What is formed by the union of two gametes during fertilization?

<p>A diploid zygote with a full set of chromosomes. (A)</p> Signup and view all the answers

What do we call the traits that can be expressed only when two copies are present?

<p>Recessive traits (A)</p> Signup and view all the answers

In what way does meiosis increase genetic diversity?

<p>Through the process of random fertilization. (C)</p> Signup and view all the answers

What does the Law of Segregation state?

<p>Each parent randomly passes one allele to their offspring (D)</p> Signup and view all the answers

What is the final result of meiosis in terms of chromosome types?

<p>Four haploid cells with distinct genetic variations. (D)</p> Signup and view all the answers

In a monohybrid cross, what does F2 generation represent?

<p>Second round of offspring (D)</p> Signup and view all the answers

What is the key characteristic of a tetrad during meiosis?

<p>It consists of four non-identical sister chromatids. (D)</p> Signup and view all the answers

Which condition is characterized by the presence of an extra X chromosome in males?

<p>Klinefelter Syndrome (C)</p> Signup and view all the answers

What type of cells are formed at the end of spermatogenesis?

<p>Four motile sperm cells (C)</p> Signup and view all the answers

What is true about the genotype of an organism?

<p>It describes the genetic makeup in terms of alleles (A)</p> Signup and view all the answers

What is the role of cytoplasmic division in oogenesis?

<p>To create one large functional egg and smaller polar bodies. (B)</p> Signup and view all the answers

Which statement about meiosis is correct?

<p>Meiosis results in gametes with half the chromosome number (B)</p> Signup and view all the answers

What is the genetic outcome when a homozygous dominant is crossed with a homozygous recessive?

<p>All offspring will be heterozygous (B)</p> Signup and view all the answers

What does aneuploidy refer to?

<p>An abnormal number of chromosomes (D)</p> Signup and view all the answers

Which of the following best describes a true-breeding plant?

<p>It consistently produces offspring with specific traits (A)</p> Signup and view all the answers

How are fossils used to provide evidence of evolution?

<p>They document the history of life, showing the differences between past and present organisms. (C)</p> Signup and view all the answers

What is the significance of transitional fossils in the study of evolution?

<p>They exhibit traits that link ancient ancestors with their descendants. (C)</p> Signup and view all the answers

What does the concept of biogeography help explain regarding species distribution?

<p>Different continents can host species that have evolved under similar conditions. (B)</p> Signup and view all the answers

What do homologous structures indicate about different species?

<p>They share a common ancestor despite having different functions. (B)</p> Signup and view all the answers

Which of the following is an example of vestigial organs?

<p>Whale tailbones (D)</p> Signup and view all the answers

What evidence supports the idea of a common ancestor for all life?

<p>The same basic genetic machinery of DNA and RNA across species. (A)</p> Signup and view all the answers

How is the absolute age of a fossil determined?

<p>Using radioactive dating to measure isotopes within the fossil. (D)</p> Signup and view all the answers

What feature distinguishes convergent evolution from divergent evolution?

<p>It results in related species evolving similar traits due to environmental pressures. (D)</p> Signup and view all the answers

What do the early similarities in embryos of different species suggest?

<p>These species likely shared a common ancestor. (A)</p> Signup and view all the answers

Which statement about the Last Universal Common Ancestor (LUCA) is accurate?

<p>All existing life forms can trace back to LUCA. (C)</p> Signup and view all the answers

What concept did Lamarck propose regarding species and characteristics?

<p>Species can acquire characteristics during their life and pass them to offspring. (D)</p> Signup and view all the answers

Which statement best describes uniformitarianism in geology?

<p>Slow processes over long periods lead to significant geological changes. (C)</p> Signup and view all the answers

Darwin's observation of finches on the Galapagos Islands contributed to his understanding of which concept?

<p>Natural selection based on environmental adaptations. (D)</p> Signup and view all the answers

What evidence did Darwin gather to support his theory of evolution on the HMS Beagle?

<p>He collected fossils and noted variations among species in different habitats. (B)</p> Signup and view all the answers

What adaptation did Darwin observe in tortoises from the Galapagos Islands?

<p>Isabela Island tortoises had features for reaching high vegetation. (D)</p> Signup and view all the answers

What did Darwin conclude from his fossil discoveries?

<p>Modern species evolved from ancient ancestors. (C)</p> Signup and view all the answers

Which of the following ideas directly challenged the view of a young Earth?

<p>Geological formations require millions of years to form. (B)</p> Signup and view all the answers

What was a significant observation Darwin made about local species diversity?

<p>Species in different environments displayed unique adaptations. (D)</p> Signup and view all the answers

What aspect of Darwin's travels influenced his theory most profoundly?

<p>The vast array of species and their adaptations to different environments. (B)</p> Signup and view all the answers

What characteristic of adaptations was highlighted in desert organisms compared to forest organisms?

<p>They have different survival strategies suited to distinct environments. (D)</p> Signup and view all the answers

What role did Charles Lyell's work play in Darwin's development of his theories?

<p>Lyell's principles showcased the importance of slow geological processes. (C)</p> Signup and view all the answers

Which of the following descriptions best fits the gradualism theory?

<p>Earth's geological features formed through a series of small, gradual changes. (A)</p> Signup and view all the answers

What main conclusion did Darwin draw regarding the variety of species he encountered during his travels?

<p>Separate species arose from ancestral forms due to isolation. (C)</p> Signup and view all the answers

Flashcards

Biodiversity

The variety of life on Earth, including all living things, from single-celled organisms to complex multicellular ones.

Biological species

A group of organisms that can breed and produce fertile offspring. For example, Labrador Retrievers and Poodles can interbreed and their offspring are fertile, so they are the same species.

Genetic Diversity

The variation of genes within a single species. For example, different breeds of dogs have different genes for coat color and size.

Species Diversity

The variety of different species in an ecosystem and their relative abundance. For example, a rainforest has a high species diversity with many different types of plants and animals.

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Ecological Diversity

The variety of biological communities in a given region, influenced by both living (biotic) and non-living (abiotic) factors. For example, the differences in plant and animal communities between a desert and a rainforest.

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Taxonomy

The branch of biology that classifies organisms and gives them scientific names.

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Binomial Nomenclature

A system of naming organisms using two words: the genus and species.

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Domain

The broadest level of classification in the Linnaean system, grouping organisms based on fundamental cellular characteristics.

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Species

The most specific level of classification, grouping organisms that can interbreed and produce fertile offspring.

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Phylogeny

The evolutionary history of an organism, showing how it has changed over time.

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Phylogenetic Tree

A diagram that shows the evolutionary relationships between different groups of organisms.

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Homologous Structures

Structures in different species that are similar because of common ancestry.

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Analogous Structures

Structures in different species that are similar in function, but not in structure.

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Vestigial Structures

Structures that have become reduced in size over time, often considered 'leftovers' from an ancestor.

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Morphology

Classification based on the structural features of an organism.

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Biochemical Similarities

The use of similarities in chemical compounds found in cells to demonstrate relationships between organisms.

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Genetic Similarities

The use of similarities in DNA sequences to determine the evolutionary relationships between organisms.

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Cladistics

A branch of biology that focuses on classifying organisms based on their evolutionary relationships.

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Shared character

A feature that all members of a group have in common.

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Derived character

A feature that evolved in a particular group.

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Clade

A group of organisms that includes an ancestor and all of its descendants.

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Cladogram

A diagram that depicts evolutionary relationships among a group of organisms.

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Domain Bacteria

The group of organisms that includes bacteria and archae-bacteria, both prokaryotic and unicellular.

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What is a biological species?

A group of organisms that can breed and produce fertile offspring.

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What are protists?

A group of organisms that are neither plant, animal, nor fungi.

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What are the characteristics of fungi?

Cell walls are made of chitin, have no chloroplasts, and are heterotrophic.

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What are Archaebacteria?

They are unicellular and live in extreme environments.

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What makes viruses non-living?

They are not alive and cannot reproduce on their own.

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What is a capsid?

A protein shell that protects the virus's genetic material.

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What is a bacteriophage?

A virus that specifically infects bacteria cells.

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What is the lytic cycle?

The virus replicates inside the host cell and bursts out, killing the cell.

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What is the lysogenic cycle?

The virus incorporates its DNA into the host cell's DNA, replicating without killing the cell.

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How do viruses reproduce?

They are particles that only reproduce by using a host cell.

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S Phase

The phase of the cell cycle where DNA is replicated, creating two identical copies of each chromosome.

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G1 Phase

The primary growth phase of a cell following division, where the cell grows in size.

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G2 Phase

The secondary growth phase after DNA replication, where the cell prepares for division.

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M Phase (Mitosis)

The phase of the cell cycle where the nucleus divides, resulting in two daughter cells.

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Apoptosis

The process of programmed cell death, where a cell is systematically dismantled and broken down.

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Tumor

A mass of cancerous cells that grow uncontrollably and may spread to other parts of the body.

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Anaphase

The process where sister chromatids separate and move to opposite poles of the cell during mitosis.

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Telophase

The final phase of mitosis where the nuclear envelope reforms around each set of chromosomes, and the cytoplasm divides.

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Trait

A characteristic that distinguishes an organism, determined by inheritance or environmental factors.

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Heredity

The transmission of genetic information from one generation to the next.

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DNA

The molecule containing genetic information, found in chromosomes within the cell's nucleus.

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Genes

Units of information within DNA that code for specific proteins, leading to visible traits or functions.

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Genetics

The study of genes, heredity, and genetic variation in organisms.

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Lysogenic Cycle

The process by which a virus inserts its genetic material into a host cell's genome, remaining dormant and replicating along with the host.

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Lytic Cycle

A viral replication cycle where the virus takes over the host cell, replicates itself, and destroys the host cell.

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Lysogeny

The stage in the lysogenic cycle where viral DNA remains dormant within the host cell.

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DNA Replication

The process of copying DNA to create an identical copy, essential for cell division.

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Chromatin

A long, unwound strand of DNA found in eukaryotic cells, making up chromosomes.

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Chromosome

A packaged form of DNA found in eukaryotic cells, containing genetic information.

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Locus

The location of a gene on a chromosome.

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Genome

The set of all genes present in an organism.

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Transcription

The process by which DNA is converted into RNA, a messenger molecule that carries genetic information.

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Translation

The process by which RNA is used to create proteins, following the genetic code.

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Chromosomes and Centromeres

The number of centromeres in a cell is equal to the number of chromosomes.

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Chromatids Before and After S Phase

Before S phase, each chromosome in a parent cell consists of only one chromatid. After the S phase, DNA replication occurs, resulting in two sister chromatids joined at the centromere, now forming a single chromosome.

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Telomeres: Protecting Chromosome Ends

Telomeres are protective caps at the ends of chromosomes that consist of repetitive DNA sequences. They prevent the loss of important genetic information during DNA replication.

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What is a Mutation?

A mutation is any change in the DNA sequence. These changes can occur spontaneously or due to external factors called mutagens.

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Importance of Mutations

Mutations are critical for genetic variation, which fuels evolution. They can have both positive and negative effects on an organism's traits.

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What is Asexual Reproduction?

Asexual reproduction involves a single parent cell dividing to produce two identical daughter cells. Examples include fragmentation, mitosis, and binary fission.

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What is Sexual Reproduction?

Sexual reproduction involves the fusion of two cells (egg and sperm) to create a new cell (zygote) that is not identical to either parent.

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Diploid Cells

Diploid cells have two copies of each chromosome, one from each parent. Examples include zygotes, embryos, and most body cells.

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Haploid Cells

Haploid cells contain only one copy of each chromosome. Examples include gametes (sperm and egg cells) and spores.

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What is Meiosis?

Meiosis is a specialized cell division process that produces four haploid cells from one diploid parent cell. It is crucial for sexual reproduction.

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Diploid

A cell containing two sets of chromosomes, one set from each parent.

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Haploid

A cell containing one set of chromosomes.

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Non-homologous chromosomes

Chromosomes that do not pair up during meiosis. They have different genes and do not have the same structure.

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Homologous chromosomes

Chromosomes that pair up during meiosis. They have the same genes, but might have different versions (alleles).

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Crossing over

The process where homologous chromosomes exchange genetic material.

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Tetrad

The four chromatids of a pair of homologous chromosomes aligned together during meiosis.

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Metaphase 1

The stage of meiosis where homologous chromosomes align in the middle of the cell.

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Gametogenesis

The process of creating gametes (sperm and egg cells).

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Spermatogenesis

The process of forming sperm cells.

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Oogenesis

The process forming egg cells.

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Nondisjunction

The failure of chromosomes to separate properly during meiosis.

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Prophase II

The stage of meiosis where chromosomes condense, the nuclear envelope breaks down, and spindle fibers form.

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Telophase II

The final stage of meiosis where the nuclear envelope reforms, chromosomes decondense, and the cytoplasm divides to produce four haploid daughter cells.

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Principle of Segregation

A pair of alleles separate during meiosis, so that each gamete (sex cell) receives only one allele from each pair.

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Law of Independent Assortment

Genes located on separate chromosomes are inherited independently of each other. This means that the inheritance of one gene does not influence the inheritance of another.

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Dihybrid Cross

A cross between two individuals with two different traits. For example, a cross between a plant with round, yellow seeds and a plant with wrinkled, green seeds.

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Incomplete Dominance

The hybrid (heterozygous) offspring shows a phenotype that is a blend of the two parental phenotypes. Neither allele is completely dominant.

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Codominance

Both alleles are expressed equally in the heterozygous phenotype. There is no dominant or recessive allele.

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Polygenic Trait

A trait influenced by multiple genes, resulting in a wide range of phenotypes. Examples include height, skin color, and eye color.

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Sex-Linked Trait

Genes located on sex chromosomes (X or Y). These traits are often expressed differently in males (XY) and females (XX) because males only have one X chromosome.

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Evolution

The process by which modern organisms have descended from ancient organisms. It involves changes in the heritable characteristics of a population over generations.

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Scientific Theory

A well-substantiated explanation of some aspect of the natural world, supported by a large body of evidence. It is not a guess or a hunch.

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Uniformitarianism

A hypothesis that geological changes occur very gradually over long periods of time by processes that are still happening today.

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Catastrophism

The idea that geological changes are caused by sudden and dramatic events, different from the processes we see today.

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Georges Cuvier

This pioneer in paleontology discovered that fossils in deeper, older rock layers were increasingly different from living species, suggesting evolution over time.

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James Hutton

This scientist proposed that Earth's features were formed slowly over long periods of time by processes like erosion and mountain formation.

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Jean-Baptiste Lamarck

This scientist proposed that acquired traits, like muscle growth, could be passed down to offspring.

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Gradualism

Charles Darwin's understanding of this concept helped him realize that Earth was old enough for evolution to occur.

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Thomas Malthus

Darwin was influenced by this person's ideas about population growth and resource limitations, which helped him develop his theory of natural selection.

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Natural Selection

Darwin's theory of evolution by natural selection explains how species change over time by inheriting favorable traits.

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Theory of Acquired Characteristics

This theory suggests that species change over time by inheriting traits acquired during their lifetime, which was later proven incorrect.

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Paleontology

The study of fossils, which provides evidence for evolution and changes in Earth's history.

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Mitosis

The process of cell division that produces two genetically identical daughter cells.

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Meiosis

The process of cell division that produces four genetically unique daughter cells, each with half the number of chromosomes as the parent cell.

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Aneuploidy

A condition where an individual has an abnormal number of chromosomes.

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Monosomy

A condition where an individual has only one chromosome instead of a homologous pair.

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Trisomy

A condition where an individual has three homologous chromosomes instead of a pair.

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Polysomy

A condition where an individual has three or more of a specific chromosome.

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Down Syndrome

A genetic condition caused by trisomy 21, resulting in a distinctive physical appearance, mild to moderate intellectual disability, and other health concerns.

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Klinefelter Syndrome

A genetic condition caused by trisomy 23 (47, XXY), resulting in male sex characteristics, lower testosterone production, and higher estrogen production.

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Triple X Syndrome

A genetic condition caused by trisomy 23 (47, XXX), occurring only in females, often with no or mild symptoms.

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Turner Syndrome

A genetic condition caused by monosomy 23 (45, XO), resulting in short stature, improperly developed ovaries, webbed neck, and other health concerns.

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Chromosomal Structural Rearrangements

Changes in the structure of chromosomes, including duplications, deletions, inversions, and translocations.

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Enhanced First Trimester Screening (eFTS)

A type of prenatal testing performed in the first trimester to screen for Down syndrome and other genetic conditions.

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Noninvasive Prenatal Testing (NIPT)

A non-invasive prenatal test that uses fetal DNA circulating in maternal blood to detect genetic conditions.

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Amniocentesis

A prenatal test performed in the second trimester that involves taking amniotic fluid to analyze fetal cells for genetic conditions.

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Transmutation

The idea that species can slowly change over time, passing on acquired traits to offspring.

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Fossil

The preservation of remains or traces of ancient organisms in rock, ice, etc.

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Adaptation

Characteristics that help organisms survive and reproduce in their specific environment.

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Fixity of Species

The idea that species have always existed exactly as they do now, unchanged for all time.

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Geology

The study of the Earth's history and its structure, including fossils and rock formations.

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Darwin's Finches

Darwin's observations on the Galapagos Islands, where he saw different species of finches with unique beak shapes adapted to their specific food sources.

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Darwin’s Voyage on the HMS Beagle

Darwin's journey around the world on the HMS Beagle, where he collected specimens and made observations that led to his theory of evolution.

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Survival of the Fittest

Darwin's theory that organisms with the most beneficial traits are more likely to survive and reproduce.

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Fitness

The ability of an individual to survive and reproduce in its specific environment.

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Natural Variations

Variations among individuals within a population that are inheritable. These variations allow for natural selection to occur, as some traits are more advantageous than others.

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Struggle for Existence

In any population, there are more offspring produced than can survive. This leads to competition for resources.

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Descent with Modification

The idea that all living organisms share a common ancestor and have diverged over time, accumulating different adaptations.

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Artificial Selection

A process where humans intentionally select organisms with desirable traits to breed, creating changes in the population over generations.

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Evolutionary Change

The process by which a species evolves over time, adapting to its environment and becoming more suited to its surroundings.

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Fossil Record

The fossil record demonstrates the history of life on Earth by showcasing organisms that no longer exist, often resembling current species, indicating change over time.

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Relative Age of Fossils

A relative age describes an object's age compared to other objects. In strata (rock layers), fossils found lower down are considered older than those found in higher layers.

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Absolute Age of Fossils

Determining the actual age of a fossil in years, often achieved using radioactive dating techniques. These methods analyze the breakdown of radioactive isotopes within the fossil.

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Transitional Fossils

Transitional fossils bridge evolutionary gaps, showcasing features shared by both ancient ancestors and their descendants, providing crucial links in the evolutionary chain.

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Biogeography

The study of organism distribution across geographical areas. It helps explain how similar species developed in different locations due to similar environmental pressures even though they are not related.

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Divergent Evolution

When two or more related species become increasingly dissimilar over time due to evolutionary adaptations to different environments.

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Convergent Evolution

When unrelated species evolve similar characteristics and structures due to adaptation to similar environments.

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Vestigial Organs

Vestigial organs are remnants of structures that were functional in ancestral organisms, but have lost their original function over time, providing evidence of evolutionary history.

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Study Notes

Classification of Living Things

  • Biodiversity is the variety of life on Earth, encompassing all living things (multicellular and unicellular).
  • Taxonomy (the classification of living things) is needed.
  • Biological species: Organisms that can interbreed and produce fertile offspring. (e.g., Labradors and Poodles are the same species, resulting in fertile Labradoodles). (e.g., Zorses are infertile, indicating horses and zebras are different species).
  • Three Levels of Biodiversity:
    • Genetic diversity: Variety of genes within a species.
    • Species diversity: Number and variety of species in an ecosystem.
    • Ecological diversity: Variety of biological communities in terrestrial and aquatic ecosystems.
  • Classification: Scientists group and classify organisms based on structural similarities and evolutionary relationships.
  • Darwin's Theory of Evolution: Organisms produce more offspring than can survive. Those best adapted to their environment survive, reproduce, and pass on their traits, leading to species diversity.
  • Taxonomy: The branch of biology that names and classifies organisms.
  • Early Attempts of Classification (Aristotle): Categorized organisms into animals (land, water, air) and plants (herbs, shrubs, trees). Limitations of this system.
  • Binomial Nomenclature (Linnaeus): A two-part scientific naming system (Genus species) based on structural similarities. Uses Latin. Organisms are in groups called Kingdoms (Plant, Animal) later divided into smaller groups (Phylum/Division, Class, Order, Family, Genus, Species), now with Domains (Domain, Kingdom, etc.).
  • Domains of Life: Three domains: Bacteria, Archaea, and Eukarya.
    • Bacteria and Archaea are single-celled.
    • Eukarya includes multicellular organisms.

Modern Taxonomy: Phylogeny

  • Phylogeny: The evolutionary history of an organism.
  • Phylogenetic tree: Shows evolutionary relationships among organisms.
  • Modern taxonomy uses multiple lines of evidence (not just morphology) including cellular organization, evolutionary relationships, embryological similarities, biochemical similarities, and genetic similarities to build phylogenetic trees.

Morphology

  • Homologous structures: Similar structures in different species due to common ancestry (e.g., bones in bird wings, bat wings, human arms, and whale flippers).
  • Analogous structures: Similar function but different structure (e.g., bird wings and butterfly wings).
  • Vestigial structures: Reduced structures with little or no function, inherited from ancestors (e.g., human appendix, whale hip bone).

Cellular Organization, Evolutionary Relationships, Biochemical Similarities, Genetic Similarities

  • Comparing cell structures, evolutionary history, chemical compounds, and genetic codes provides evidence of relationships between organisms.
  • The more similar the DNA sequence, the more recently organisms shared a common ancestor.

Embryological Similarities

  • Similarities in embryological development also indicate evolutionary relationships (e.g., amniotic sac in reptiles, birds, mammals).

Cladistics

  • Cladistics is a new method of classifying based on evolutionary innovations (shared and derived characters).
  • Clades: Groups containing an ancestor and all its descendants.
  • Cladogram: Diagram of evolutionary relationships based on shared derived characters.

Kingdoms and Domains

  • Scientists have refined classification systems as new discoveries were made.
  • Three-Domain system: The modern system
    • Domains: Bacteria, Archaea, and Eukarya;
    • Kingdoms: Protista, Fungi, Plantae, Animalia; etc.
  • Comparison of Three Domains: Table showing cell type, cell structure, cell organization, and feeding mode for Bacteria, Archaea, and Eukarya kingdoms.

Viruses

  • Seven Characteristics of Life (MRS GREN): Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition.
  • Viruses: Non-living particles requiring a host cell for reproduction; consists of a capsid, DNA or RNA.
  • Viral Structure: Nucleic acid core surrounded by a protein coat (capsid) – some have outer lipid membranes.
  • Viral Replication: Lytic or Lysogenic cycles. The lytic cycle destroys the host cell. The lysogenic cycle integrates viral DNA into the host DNA.

Genetics

  • DNA: Complex molecule storing genetic information, organized into genes.
  • Heredity: Passing of genetic information from generation to generation.
  • DNA Structure: Double helix composed of nucleotides (sugar, phosphate, and base).
  • Base Pairs: A with T, and C with G.
  • Chromosomes: Organized packages of DNA. Humans have 46.
  • Genes and Loci: Genes are sections of DNA that code for proteins. The locus is a gene's location on a chromosome.
  • DNA → RNA → Proteins: Transcription and translation.

Genetic Processes

  • Cell Cycle: Series of events leading to cell division.

  • Mitosis: Process of cell division producing two genetically identical daughter cells. Stages: Prophase, Metaphase, Anaphase, and Telophase.

  • Cytokinesis: Division of cytoplasm after mitosis.

  • Apoptosis: Cell death.

  • Cancer: Uncontrolled cell division.

  • Chromosomes vs Chromatids: Chromosomes consist of sister chromatids joined at the centromere.

  • Telomeres: Protective caps at the ends of chromosomes.

  • Types of Mutations: Spontaneous vs induced. Discuss mutagens.

  • Meiosis: Two-part cell division for creating gametes. Stages: Meiosis I (separate homologous chromosomes, crossing over) and Meiosis II (separate sister chromatids).

  • Nondisjunction: Error in chromosome separation, leading to aneuploidy (e.g., Trisomy 21, Klinefelter Syndrome, Turner Syndrome, Triple X Syndrome)

  • Gametogenesis: Production of gametes (sperm and egg) through meiosis. Compare spermatogenesis and oogenesis.

  • Nondisjunction: Errors during meiosis can result in gametes with abnormal chromosome numbers (e.g., Trisomy 21, Turner Syndrome). This can lead to various syndromes.

  • Various prenatal testing methods for diagnosing nondisjunction.

Mendelian Genetics

  • Mendel's Experiments: Used pea plants to study inheritance patterns.
  • Alleles: Different forms of a gene (dominant and recessive).
  • Law of Segregation: Each parent passes one allele for each trait.
  • Genotype: Genetic makeup.
  • Phenotype: Physical appearance.
  • Monohybrid cross: Cross between two individuals differing by a single trait.
  • Complete dominance vs incomplete dominance vs. codominance: Describe the different patterns.

Beyond Mendel

  • Incomplete dominance: Neither allele is completely dominant. An intermediate phenotype is observed.
  • Codominance: Both alleles are expressed equally in the heterozygous state.
  • Multiple alleles: More than two alleles for a trait (e.g., human blood types).
  • Polygenic traits: Traits controlled by multiple genes (e.g., human height, skin color).
  • Sex-linked traits: Traits determined by genes on sex chromosomes.

Evolution

  • Evolution: Change in heritable characteristics in a population over generations.
  • Biological Diversity: Variety of living things on Earth.
  • Evidence for Evolution: Fossil record, biogeography, comparative anatomy, embryology, biological molecules.
  • Natural Selection: Process where organisms with advantageous traits are more likely to survive and reproduce. Explains how biodiversity arises.
  • Charles Darwin: Developed the theory of natural selection. His voyage on the HMS Beagle and observations of species variation were crucial.
  • Descent with modification: All species descended from a common ancestor, evolving and adapting over time.
  • Natural selection principles: Individual organisms don't evolve, populations do, Traits are amplified/diminished by the environment and are inherited, environmental factors vary, organisms compete for resources, and fitness is determined by an organism's ability to survive and reproduce (adaptations).
  • Evidence for evolution: Fossil record, strata, transitional fossils, geographic distribution of living organisms, comparative anatomy, vestigial organs, embryology, biological molecules, last universal common ancestor (LUCA).
  • Comparative anatomy: Homologous and analogous structures, and vestigial organs are all clues to how species have evolved from a common ancestor.

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Test your knowledge on key concepts of biological species and diversity in ecosystems. Dive into Darwin’s Theory of Evolution and understand the implications of genetic diversity and hybrid organisms. Perfect for students studying biology at an intermediate level.

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