Chapter 2

Question 1

What is evolution?

Answer 1

The change in genetic composition of a population over time

Question 2

What is a “heritable trait”?

Answer 2

Trait or characteristic passed from parent to offspring

Question 3

What is natural selection?

Answer 3

Survival/ reproduction of individuals who are best adapted to environment

Question 4

Why do we care about evolution, heritability, and natural selection?

Answer 4

Because over the course of millions of years, the three processes and their interplay have resulted in all of us.

Question 5

Diverse methods of reproduction

Answer 5

• heritable traits are encoded by genes which are linear Stretches of DNA.
• • DNA is contained in chromosomes within the nucleus of each cell in an organism
• the human genome contains an estimated 20,000-25,000 genes.
• information contained in genes, interacting with the environment over time, results in process of evolution.

Question 6

Why do we care about conjugation?

Answer 6

Because it is by this process that bacteria “swap” DNA, and its how they become resistant to antibiotics

Question 7

Diverse methods of Reproduction have evolved

Answer 7

• organisms that contain a nucleus in their cells are eukaryotes. Eukaryotes can be single celled or multicellular
• diversification of eukaryotic animals occurred in the Cambrian explosion 545 million years ago
• nearly all eukaryotic organisms can reproduce sexually. It’s results from the mixing of DNA from each parent through two specialized cells called gametes
• gametes are usually haploid
• haploid gametes are produced by specialized cell division known as meiosis, which takes place in the gonads

Question 8

What are gonads?

Answer 8

A gonad is an organ that produces gametes. In humans, female gonad ovaries, male testes.

Question 9

What are gametes?

Answer 9

A specialized cell that can fuse with another to form an organism. In humans, sperm and ovum

Question 10

Why are there two sexes?

Answer 10

-“male” nutrient-poor, motile small, gametes and “female” large, nutrient rich but cumbersome

Question 11

Evolution has led to diverse methods of sex determination

Answer 11

Sex may be determined by

1. Chromosomes
2. Environment
   - in mammals, sex is determined by sex chromosomes (XX=female, XY=male)
   - in some reptilian species, sex is determined by the temperature at which eggs are incubated