Section 3

Question 1

Mitosis

Answer 1

Nuclear division in which the chromosome number stays constant. Produces 2 daughter cells each having the same # of chromosomes as the parent nucleus.

Question 2

Cytokinesis

Answer 2

divides the cell in 2 equal parts with equal # of chromosomes at the end of mitosis.

Question 3

Structure of chromosome

Answer 3

DNA double helix is wound at intervals around a core of 8 histones molecules.

Question 4

Centromere

Answer 4

Holds chromatids together

Question 5

Chromatid

Answer 5

Chromosome strand

A complete copy of a chromosome.

Question 6

Why do cells divide?

Answer 6

To replace old, dead, or damaged cells. So living things can grow.

Question 7

Meisosis

Answer 7

Form of cell division that creates 4 haploid cells from 1 diploid cell. It is used to form gametes. (Sperm/egg)

Question 8

Diploid

Answer 8

Contains 2 sets of chromosomes. Human cells contain 23 pairs of homologous chromosomes.

Question 9

Haploid

Answer 9

Only 1 set of chromosomes. Human sperm/egg cells have 23 chromosomes.

Question 10

Down syndrome

Answer 10

Trisomy 21 (3 copies)

Question 11

Female

Answer 11

2 X chromosomes at 23rd position

Question 12

Male

Answer 12

X and Y chromosome at 23rd position

Question 13

Klinefelters syndrome

Answer 13

2 or more X chromosomes in males 23rd position

Question 14

Turners syndrome

Answer 14

1 X sex chromosome (only affects females)

Question 15

How do mutations occur?

Answer 15

Sometimes, a pair of homologous chromosomes fails to separate during meiosis. Results in egg or sperm with extra copy of chromosome.