Chapter 7: Cellular Replication and Variation

Question 1

What is meiosis?

Answer 1

A two-phase type of cellular division in which the chromosome number of a cell is halved to the haploid number; meiosis is the basis of gamete formation in animals and spore formation in plants

Question 2

What is a locus?

Answer 2

The position a gene occupies in a chromosome

Question 3

What are alleles?

Answer 3

One of the different versions of the same gene (at the same locus) determined by small differences in the DNA sequence of the gene

Question 4

What is a genotype?

Answer 4

The alleles present in the cells of an organism

Question 5

What are chromatids?

Answer 5

A daughter strand of a duplicated chromosome that is joined by a centromere - (refer to figure 7.1.2 pg 141 for more detail)

Question 6

What is an autosome?

Answer 6

A chromosome that is the same in both males and females of a species; autosomes do not include sex chromosomes

Question 7

What is diploid (2n)?

Answer 7

Describes a cell or organism that has a genome comprising two copies of each chromosome, represented by 2n

Question 8

What is haploid (n)?

Answer 8

Describes a cell or organism that has a genome that contains one copy of each chromosome, represented by n

Question 9

What is interphase?

Answer 9

The stage between nuclear divisions

Question 10

What are the inputs and outputs of meiosis?

Answer 10

Refer to figure 7.1.3 pg 142 for information

Question 11

What is a synapsis?

Answer 11

The pairing of homologous chromosomes

Question 12

What is a bivalent?

Answer 12

Visible bodies in a cell during prophase I of meiosis, which is made up of two homologous chromosomes joined together

Question 13

What are chiasmata?

Answer 13

The point of contact between homologous chromosomes during prophase I of meiosis

Question 14

What is cytokinesis?

Answer 14

The division of the cytoplasm

Question 15

What is the process of meiosis I and II?

Answer 15

Refer to figure 7.1.4 pg 143 for information

Question 16

What is crossing over?

Answer 16

An event during meiosis in which homologous chromosomes exchange segments with one another

Question 17

What is oogenesis?

Answer 17

The process in the ovary that results in the production of female gametes

Question 18

What is a polar body?

Answer 18

A very small cell produced during oogenesis, containing a nucleus, but very little cytoplasm (figure 7.1.6 pg 144 for diagram)

Question 19

What is spermatogenesis?

Answer 19

The continuous production of sperm cells in testis (figure 7.1.7 pg 145 for diagram)

Question 20

What are the three main differences between oogenesis and spermatogenesis?

Answer 20

• Oogenesis produces one egg and a polar body, spermatogenesis produces four sperm
• At birth, an ovary produced contains all the cells that will ever develop into eggs. Sperm is produced continuously
• Sperm are produced continuously, whereas oogenesis has long breaks between stages of division.

Question 21

What is an independent assortment?

Answer 21

The process by which the paternal and maternal chromosomes of each homologous pair behave independently of the other homologous pairs as they separate in meiosis