Unit 2 Classical Genetics Exam

Question 1

Solve the following crosses:

Answer 1

a. Complete dominance mono hybrid cross

b. Incomplete Dominance

c. Codominance

d. Multiple alleles

e. Blood typing

f. Sex linked

Question 2

Define Gamete

Answer 2

A gamete is a reproductive cell of an animal or plant.

Question 3

Define Autosome

Answer 3

An autosome is one of the numbered chromosomes, as opposed to the sex chromosomes.

Question 4

Define allele

Answer 4

Two alternate forms of a trait

Question 5

Define genotype

Answer 5

the genetic makeup of an organism.

Question 6

Define homozygous

Answer 6

having two identical alleles of a gene.

Question 7

Define dominant

Answer 7

a dominant trait or gene or most important, powerful, or influential.

Question 8

Define phenotype

Answer 8

The observable physical properties of an organism (what the genotype shows)

Question 9

Define heterozygous

Answer 9

having two different alleles of a gene.

Question 10

Define recessive

Answer 10

a recessive trait or gene or less important (not dominant)

Question 11

which parent dictates the childs sex?

Answer 11

The sex of the child is determined by the father, as a sperm cells transmit either the Y or X chromosome.

Question 12

Possible genotypes for blood types

Answer 12

Blood Type Genotype
Blood Type A Genotypes AA or AO
Blood Type B Genotypes BB or BO
Blood Type AB Genotype AB
Blood Type O Genotype OO

Question 13

What is the difference between a gene and a chromosome?

Answer 13

Genes are segments of your DNA, Chromosomes carry DNA in cells.

Question 14

What is the purpose of meiosis?

Answer 14

to create gametes for sexual production with half the genetic material of the parent cells.

Question 15

How many chromosomes are at the beginning of meiosis?

Answer 15

46 chromosomes

Question 16

How many chromosomes are at the end of meiosis?

Answer 16

23 chromosomes.

Question 17

Understand how chromosomes divided through phase 1 and phase 2 of meiosis

Answer 17

There are two divisions in meiosis; the first division is meiosis I: the number of cells is doubled but the number of chromosomes is not. This results in 1/2 as many chromosomes per cell. The second division is meiosis II: this division is like mitosis; the number of chromosomes does not get reduced.

Question 18

Define nondisjunction

Answer 18

The failure of the chromosomes to separate, which produces daughter cells with abnormal numbers of chromosomes.

Question 19

Define crossing over

Answer 19

the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.

Question 20

Describe the steps of meiosis

Answer 20

Interphase: The cell prepares for division by replicating its DNA, resulting in two identical sister chromatids held together by a centromere.
Prophase I: Chromosomes condense, homologous chromosomes pair up and exchange genetic material through crossing over, forming chiasmata. The nuclear envelope breaks down, and spindle fibers begin to form.
Metaphase I: Homologous chromosome pairs align at the cell’s equator, attached to spindle fibers at their centromeres.
Anaphase I: Homologous chromosomes separate and move toward opposite poles of the cell, pulled by spindle fibers.
Telophase I: Chromosomes arrive at opposite poles, and nuclear membranes may form around each set of chromosomes. The cell undergoes cytokinesis, resulting in two haploid daughter cells, each containing one set of chromosomes.
Prophase II: Chromosomes condense again, and the nuclear envelope breaks down if it reformed in telophase I. Spindle fibers begin to form.
Metaphase II: Chromosomes align at the cell’s equator, attached to spindle fibers at their centromeres.
Anaphase II: Sister chromatids separate and move toward opposite poles of the cell, pulled by spindle fibers.
Telophase II: Chromatids arrive at opposite poles, and nuclear envelopes form around each set of chromosomes. The cell undergoes cytokinesis again, resulting in four haploid daughter cells, each containing half the number of chromosomes as the original parent cell.

Question 21

Understand how to read a pedigree

Question 22

What is the purpose of a karyotype

Answer 22

To help identify genetic problems as the cause of a disorder or disease.

Question 23

How many chromosomes do humans have?

Answer 23

46 chromosomes in total.

Question 24

Understand how to read a karyotype