Chapter 2 Sex and Evolution

Question 1

Evolution

Answer 1

The change in the genetic makeup of living populations over time.

Question 2

Heritable

Answer 2

Capable of being passed down from parent to offspring

Question 3

Gene

Answer 3

a stretch of DNA that is ttranscribed as a functional unit; a unit of inheritance.

Question 4

DNA

(Deoxyribonucleic Acid)

Answer 4

the linear molecule that forms the chemical basis of genes in all species except some viruses.

Question 5

Chromosome

Answer 5

a rod-shaped nuclear organelle composed of DNA and associated proteins

Question 6

Genome

Answer 6

An organism’s entire complement of DNA, including all its genes.

Question 7

Conjugation

Answer 7

Contact between two bacteria accompanied by the transfer of a short stretch of DNA (plasmid) from one another.

Question 8

(1) Gamate
(2) Haploid
(3) Diploid

Answer 8

(1) a specialized call that fuses w another to form a new organism (sperm or ovum)
(2) Possessing healf the usual complement of chromosomes
(3) Possessing the full complement of chromosomes. All cells but gamates

Question 9

Meiosis

Answer 9

A pair of cell divisions that produces gametes; involves exchange of genetic material between homologous chromosomes & reduction of chromosome # from diploid to haploid.

Question 10

Explanations for Sexual Reproduction

Answer 10

The main idea is that it limits harmful mutations.

When organisms reproduce sexually harmful mutations can be eliminated. That’s because the offspring receives a randomly selected half of their mother’s genes and half of their father’s genes.

Also, sexual reproduciton might generate beneficial gene combinations.

Question 11

Red Queen Hypothesis

Answer 11

The idea that sexual reproduction is advantageous because it helps defend organisms againts parasites

Question 12

Why 2 sexes?

Hermaphrodite

Answer 12

Investment: the commitment or expenditure of resoruces for a goal, such as reproductive success.

An organism that combines male and female reproductive functions.

Question 13

SRY

(Sex-determining Region of the Y chromosome)

Answer 13

a gene located on the Y chromosome that causes embryo to develop as a male.

Also, there is a connection between sexes and temperature. In some animals low temperatures will develop males and high will develop females. This is not constant among all species.

Question 14

gestation

Answer 14

Bearing a young in the uterus; pregnancy

Question 15

Reproductive Strategies: Risk

Answer 15

Males

Max # of potential offspring high
May not be able to find willing mate
Risk: inability to create offspring
Seek to mate WIDELY

Females

Max # of potential offspring low
Plenty of males willing to mate w/ her
Risk: failure of offspring to survive
Therefore, seek to mate WISELY

Question 16

Pheromone

Answer 16

A volatile compound that is released by one organism and that triggers a specific behavior in another member of the same species.

Question 17

Females tend to pay attention to

Answer 17

Bodily symmetry.

Fluctuating Asymmetry; a difference between the left and right sides of the body that results from random perturbations of development.

Question 18

Proceptive Behavior

Answer 18

Behavior of females that may elicit sexual advances by males (courtship behaviors).

Question 19

Estrus

Answer 19

The restricted period within the ovarian cycle when females of some species are sexually receptive; “heat”

Question 20

What would happen if the sexes invest the same?

Answer 20

if males and females invest the same, sexual selection may not lead to any marked anatomical or behavioral differences between the sexes.

Remember the seagulls example

Question 21

Monogamy

Polygamy

Polygyny

Polyandry

Answer 21

Monogamy—2 animals form a Pair Bond
Polygamy—one animal forms a relationship w/ many members of the opposite sex:
Polygyny—many wives
Polyandry—many husbands

Question 22

Mate Guarding

Answer 22

mate remains close to female during the time in which she is fertile to keep other males away from her
Paternity (DNA) testing.

Sperim competition: By sheer force of numbers, sperm compete with the sperm of other males in the females’ reproductive tracts.