Alternate assignment for exam 3

Question 1

Somatic cell

Answer 1

A typical body cell within an organism

Question 2

Germ cell

Answer 2

A cell containing half the number of chromosomes of a somatic cell and able to unite with one from the opposite sex to form a new individual; a gamete

Question 3

Autosomal chromosome

Answer 3

control the inheritance of all an organism’s characteristics except the sex-linked ones

Question 4

Sex chromosome

Answer 4

Sex chromosomes (X,Y) contain the genetic information that instructs the developing offspring to become one sex or the other

Question 5

Meiosis

Answer 5

The type of cell division that produces haploid gametes from diploid parent cells

Question 6

Gene locus on a chromosome

Answer 6

The location of a gene on a chromosome

Question 7

Why do diploid cells ALWAYS have an even number of chromosomes?

Answer 7

Becausechromosomes comein pairs

Question 8

Zygote

Answer 8

A diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum

Question 9

Sex determination system

Answer 9

A biological system that determines the development of sexual characteristics in an organism

Question 10

What type of cell division produces sperms and eggs (gametes)?

Answer 10

meiosis

Question 11

What kind of cell division occurs so that zygote develops into a multicellular fetus?

Answer 11

mitosis

Question 12

Prophase I (meiosis 1)

Answer 12

the chromatin coils up into the chromosomes. In a process called synapsis the homologous chromosomes, each with their sister chromatids come together as pairs. The resulting structure is called a tetrad

Question 13

Metaphase I (meiosis 1)

Answer 13

tetrads align on the metaphase plate. Spindle microtubules are attached to the kinetochores at the centromeres. Crossing over between homologous chromosomes comes to an end. NOTE: spindle microtubules attached to one homologous chromosome are from one pole of the cell, and the other homologous chromosome is attached to microtubules from the other pole.

Question 14

Anaphase I (meiosis 1)

Answer 14

homologous chromosomes are pulled away from one another to opposite polls. Each chromosome is in the form of two sister chromatids attached at the centromere. At the end of anaphase there is a haploid number of chromosomes approaching the two poles of the cell.

Question 15

Telophase I (meiosis 1)

Answer 15

the chromosomes arrive at the poles, cytokinesis occurs and two haploid daughter cells are formed.

Question 16

Independent assortment of chromosomes

Answer 16

Homologous chromosomes, or tetrads, line up randomly during metaphase I on the metaphase plate before being separated during anaphase I. The total number of combinations of chromosomes that meiosis can package into gametes because of this randomization is 2n , where n is the haploid number of the organism in question

Question 17

Prophase II (meiosis 2)

Answer 17

spindle forms and moves chromosomes toward middle of cell

Question 18

Metaphase II (meiosis 2)

Answer 18

chromosomes aligned on metaphase plate. This time the kinetochores of the sister chromatids face opposite poles with the spindle microtubules attached from the corresponding poles.

Question 19

Anaphase II (meiosis 2)

Answer 19

centromeres of sister chromatids finally separate and each chromatid moves to opposite poles

Question 20

Telophase II (meiosis 2)

Answer 20

nuclei form around the haploid collection of chromosomes

Question 21

What are the three sources of genetic variability in the offspring of sexually reproducing organisms?

Answer 21

1. Crossing over during prophase I
2. Independent assortment of homologous chromosomes at metaphase I
3. Ultimately random fertilization creating the zygote

Question 22

What are the sex chromosomes in humans?

Answer 22

In humans the X and Y chromosomes are the sex chromosomes and the combination of these chromosomes determines the sex of the organism.

Question 23

What are the sex chromosomes in humans? What combination of sex chromosomes produces a female?

Answer 23

In humans, the somatic cells in females have a XX set
In humans, the somatic cells in males have a XY set
In humans the father’s sperm always determines the sex of the offspring

Question 24

What are the sex chromosomes in birds? What combination of sex chromosomes
produces a female bird? What combination produces a male bird? So, is it the hen or the rooster that determines the sex of their offspring?

Answer 24

the egg cell (mother) determines the sex of the offspring. Female birds contain one of each of the sex chromosomes (Z, W). Male birds have two of the Z chromosomes (Z, Z)