ap bio unit 5 - important points

What phase has homologous chromosomes separate to opposite poles of the cell?

Anaphase I of meiosis.

What is the ploidy number of each cell at the end of meiosis?

The ploidy number is haploid (n), with each cell containing half the original number of chromosomes.

What are two differences between mitosis and meiosis?

• Number of Divisions: Mitosis involves one division, producing two identical diploid cells, while meiosis involves two divisions, producing four genetically unique haploid cells.

• Genetic Variation: Mitosis maintains genetic consistency, while meiosis introduces genetic variation through crossing over and independent assortment.

How does crossing over increase diversity?

Crossing over increases diversity by exchanging genetic material between homologous chromosomes during prophase I of meiosis. This creates new combinations of alleles on each chromosome, leading to genetically unique gametes.

What are the laws of segregation and independent assortment?

• Law of Segregation: Each organism has two alleles for each gene, and these alleles separate during gamete formation, with each gamete carrying only one allele from each pair.

• Law of Independent Assortment: Alleles for different traits are inherited independently of each other during gamete formation, meaning the inheritance of one trait does not affect the inheritance of another.

A scientist wants to determine the odds of a child inheriting two traits. Both parents are heterozygous for both traits and the scientist wants the odds of a child displaying dominance in one trait and is recessive in the other. What are the odds?

The possible genotypes are:

1. Dominant for one trait and recessive for the other (e.g., A_bb or aaB_).

• Probability of A_bb = 34×14=316\frac{3}{4} \times \frac{1}{4} = \frac{3}{16}43​×41​=163​.

• Probability of aaB_ = 14×34=316\frac{1}{4} \times \frac{3}{4} = \frac{3}{16}41​×43​=163​.

Add the probabilities:
316+316=616=38\frac{3}{16} + \frac{3}{16} = \frac{6}{16} = \frac{3}{8}163​+163​=166​=83​.

The odds are 3/8.

4o

What is a mutation?

A mutation is a change in the DNA sequence of an organism

What do you call a mutation that occurs during anaphase one or two?

nondisjunction

At the end of meiosis two gametes are n+1 and two gametes are n-1. When did the mutation occur?

anaphase I

How do we know when we can reject the null hypothesis?

when the p-value is less than the chosen significance level (α), typically 0.05.

What happens during crossing over?

homologous chromosomes exchange segments of genetic material

What is environmental plasticity? Be sure your answer includes both genotype and phenotype

Environmental plasticity refers to an organism's ability to alter its phenotype in response to environmental changes, while its genotype remains unchanged. This means that an organism with a fixed genetic makeup (genotype) can express different traits (phenotype) depending on environmental factors, such as temperature, nutrition, or light exposure.