Lecture 33

Question 1

Life on earth started as what type of organisms

Answer 1

Haploid organisms (only 1 copy of genome, 1n)

Question 2

What was life 3.5 billion years ago

Answer 2

bacteria and other prokaryotes were haploid (1n) and reproduced by binary fission

Question 3

What was life 1.2 billion years ago

Answer 3

Early photosynthetic eukaryotes (mosses) alternate between 1n and 2n stages
gametophyte (1n) life stages give ride to a sporophyte (2n) stage

Question 4

What life cycle do plants follow

Answer 4

1n/2n life cycle

Question 5

Meiosis evolved to give ride to what

Answer 5

1n generation, that then undergoes mitosis to form gametes that combine to 2n

Question 6

Self-fertilization of egg by self sperm serves to

Answer 6

clone the plant

Question 7

Cross-fertilization of egg by other sperm promotes

Answer 7

evolution

Question 8

In higher plants what are the stages like

Answer 8

the gametophyte (1n) stage is physically reduced, completely dependent on the 2n generation

Question 9

Higher animals use meiosis to make what

Answer 9

gametes directly (no separate 1n generation so 2n becomes the gametophyte)

Question 10

What does eliminating the alternating 1n/2n life cycle allow in higher animals

Answer 10

speeds up genetic diversity

Question 11

What did eliminating the alternating the 1n/2n life cycle cause

Answer 11

distinct male and female sexes to ensure cross fertilization of sperm and egg