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Questions and Answers
What is a requirement for natural selection to occur within a population?
What is a requirement for natural selection to occur within a population?
Which process does NOT contribute to genetic variation in a population?
Which process does NOT contribute to genetic variation in a population?
What is meant by 'survival value' of a trait?
What is meant by 'survival value' of a trait?
Which of the following is NOT a competition resource among individuals of the same species?
Which of the following is NOT a competition resource among individuals of the same species?
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How does sexual reproduction contribute to genetic variation?
How does sexual reproduction contribute to genetic variation?
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What does it mean when a member of a population has 'more fitness'?
What does it mean when a member of a population has 'more fitness'?
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What effect can density-independent factors have on a population?
What effect can density-independent factors have on a population?
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What factors can limit the reproductive potential of a species?
What factors can limit the reproductive potential of a species?
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What is the purpose of flowers in flowering plants?
What is the purpose of flowers in flowering plants?
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What does a monohybrid cross study?
What does a monohybrid cross study?
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What term is used to describe the observable physical characteristics of an organism?
What term is used to describe the observable physical characteristics of an organism?
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Which of the following represents a dominant allele?
Which of the following represents a dominant allele?
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What happens during the process of pollination?
What happens during the process of pollination?
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Which of the following describes recessive alleles?
Which of the following describes recessive alleles?
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What is phenotypic plasticity?
What is phenotypic plasticity?
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What is the result of a fertilised ovule?
What is the result of a fertilised ovule?
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What does sexual selection primarily influence in species?
What does sexual selection primarily influence in species?
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Which statement correctly describes haploid cells?
Which statement correctly describes haploid cells?
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What is the significance of meiosis in gamete formation?
What is the significance of meiosis in gamete formation?
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How does the concept of heterozygous differ from homozygous?
How does the concept of heterozygous differ from homozygous?
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What does the term 'sexual dimorphism' refer to?
What does the term 'sexual dimorphism' refer to?
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Who is known as the father of genetics for his work with pea plants?
Who is known as the father of genetics for his work with pea plants?
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Which process must occur for a diploid zygote to be created?
Which process must occur for a diploid zygote to be created?
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What type of variation does the random combination of alleles during gamete fusion promote?
What type of variation does the random combination of alleles during gamete fusion promote?
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What is the primary reason males are more likely to inherit sex-linked disorders than females?
What is the primary reason males are more likely to inherit sex-linked disorders than females?
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Which of the following diseases is caused by a recessive allele on the X-chromosome?
Which of the following diseases is caused by a recessive allele on the X-chromosome?
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What type of variation describes traits that belong to distinct groups, such as blood groups?
What type of variation describes traits that belong to distinct groups, such as blood groups?
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What is the function of Factor VIII in the body?
What is the function of Factor VIII in the body?
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In using a Punnett grid to determine sex-linked traits, which chromosomes are substituted for autosomal alleles?
In using a Punnett grid to determine sex-linked traits, which chromosomes are substituted for autosomal alleles?
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Which type of variation does not have limitations on the values that can occur within a population?
Which type of variation does not have limitations on the values that can occur within a population?
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What is the typical life expectancy for individuals with untreated hemophilia?
What is the typical life expectancy for individuals with untreated hemophilia?
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What is one key difference between continuous variation and discontinuous variation?
What is one key difference between continuous variation and discontinuous variation?
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What is a characteristic of polygenic traits?
What is a characteristic of polygenic traits?
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What is the primary purpose of meiosis in sexual reproduction?
What is the primary purpose of meiosis in sexual reproduction?
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Which phase is NOT part of mitosis?
Which phase is NOT part of mitosis?
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How does DNA fit within the nucleus?
How does DNA fit within the nucleus?
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What distinguishes the end products of mitosis from those of meiosis?
What distinguishes the end products of mitosis from those of meiosis?
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What is the role of the centromere during cell division?
What is the role of the centromere during cell division?
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What can influence polygenic traits in individuals, aside from genetic factors?
What can influence polygenic traits in individuals, aside from genetic factors?
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Which of the following statements about sister chromatids is true?
Which of the following statements about sister chromatids is true?
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What is the first stage of mitosis where chromosomes become visible?
What is the first stage of mitosis where chromosomes become visible?
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Which of the following occurs during metaphase?
Which of the following occurs during metaphase?
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What event differentiates anaphase from earlier stages of mitosis?
What event differentiates anaphase from earlier stages of mitosis?
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Which of the following events occurs during telophase?
Which of the following events occurs during telophase?
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What is the final outcome of cytokinesis in animal cells?
What is the final outcome of cytokinesis in animal cells?
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How do haploid cells differ from diploid cells?
How do haploid cells differ from diploid cells?
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What is the role of vacuoles during plant cytokinesis?
What is the role of vacuoles during plant cytokinesis?
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What does the 'n' represent when indicating haploid and diploid cells?
What does the 'n' represent when indicating haploid and diploid cells?
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Study Notes
Natural Selection
- Describes how organisms better adapted to their environment survive and produce more offspring.
- Can alter traits of a population over time.
- Key characteristics of Natural Selection
- More offspring are produced than can survive
- Variation of traits within population
- Limited resources lead to competition
- Individuals better adapted to the environment survive
- Survivors reproduce
- Darwin's conclusion on natural selection
- Variation exists among members of a population
- Variation allows some individuals to be favoured over others, if all members were identical.
- Sources of genetic variation
- Mutation
- Meiosis
- Sexual reproduction
Mutations
- Changes in an organism's DNA sequence
- Create new alleles, which alter traits of a species member.
Meiosis
- A reductive division creating four haploid nuclei from a single diploid cell.
- In diagrams, the state of a cell's chromosomes is represented as a factor of “n”
- Diploid cells = 2n
- Haploid cells = n
- Haploid cells form gametes, which fuse to create a diploid zygote.
- Chromosomes in gametes contain half the chromosomes as the parent cells.
- Genetic variation arises as alleles from different parents combine.
Theory of Evolution by Natural Selection
- Overproduction: Species tend to produce more offspring than can survive to maturity.
- Variation: Individuals within a population exhibit variations in traits.
- Selection: Some individuals survive longer and reproduce more effectively than others.
- Adaptation: Traits of successful individuals become more common in the population.
Survival Value
- How useful a trait is in supporting an organism's survival.
Reproductive Potential
- The maximum number of offspring an organism could produce if no factors (limiting factors) caused their death.
- The maximum number of offspring is never reached due to environmental limitations.
Sexual Selection
- Individuals with traits that improve their success in producing offspring will pass those advantageous traits onto their offspring more than others.
- Physical differences between males and females (sexual dimorphism) are often a result of sexual selection. This is particularly common in birds.
Inheritance and Gametes
- Most cells have complete homologous chromosome pairs.
- Haploid cells contain one chromosome from each pair.
Monohybrid Cross
- Analyzing a single trait in pea plants, Mendel identified traits can skip generations or be present in individuals in different generations or both.
- Dominant alleles mask the effect of recessive alleles in a genotype
Punnett Grids
- Predict the probability of outcomes of monohybrid crosses.
Phenotypic Plasticity
- Ability for genes to alter their expression based on environmental conditions.
Phenylketonuria (PKU)
- A genetic disease caused by a mutation in a gene that creates an enzyme
- Metabolises tyrosine from phenylalanine
- Excess phenylalanine and reduced tyrosine levels in affected individuals
- A recessive genetic disorder requiring 2 recessive alleles.
Blood Type Determination
- There are four blood types: A, B, AB and O.
- Based on the presence of antigens
- Punnett grids used to determine probabilities of blood type in offspring.
- Each allele represents either the presence or absence of a protein IA and IB alleles both contribute to the phenotype and produce an AB phenotype, an example of co-dominance, where both alleles are expressed.
Incomplete Dominance
- Red and white alleles mix in the offspring to create a pink phenotype.
- Trait alleles produce a phenotype that is a blend of both alleles.
Sex-Linked Traits
- Genes located on sex chromosomes
- Males have a higher probability of being affected by sex-linked traits because they inherit one X chromosome.
- Examples of sex-linked traits are red-green colour blindness, and haemophilia.
Pedigrees
- Chart diagrams showing the inheritance of traits through generations within a family.
Autosomal vs Sex-linked Traits
- Autosomal traits: Non-sex chromosomes
- Sex-linked traits: Located on sex chromosomes (X or Y)
- Males more likely to be affected by recessive sex-linked traits, as males only have one X-chromosome (females have two).
Continuous Variation
- Variations without discrete categories
- Often polygenic (influenced by multiple genes).
- Example: height, weight, hair color. Often displayed as a bell curve or histogram.
Cell and Nuclear Division
- Mitosis: Creates genetically identical daughter cells.
- Meiosis: A reduction division creating four haploid gametes from a single diploid cell.
- Both involve DNA replication and chromosome separation.
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Description
Explore the concepts of natural selection, mutations, and meiosis in this quiz. Understand how organisms adapt to their environments and how genetic variation occurs. Test your knowledge on Darwin's conclusions and the mechanisms of evolution.
