12th grade cells, genetics and evolution

Question 1

A cladogram branches in this order: lamprey, shark, frog, lizard, mouse. New traits: jaws appears before the shark branch; four limbs appears before the frog branch; amniotic egg appears before the lizard branch; hair appears before the mouse branch. Does the mouse have jaws?

• A. yes
• B. no

Question 2

Why does DNA with a high percentage of C and G need more energy to separate its strands?

• A. C–G pairs are held by three hydrogen bonds, A–T pairs by two
• B. A and T are not paired
• C. C and G are heavier atoms
• D. C–G DNA is single-stranded

Question 3

Is this passive or active transport: the sodium–potassium pump?

• A. passive (no ATP needed)
• B. active (uses ATP)

Question 4

Why is the cell membrane described as a "fluid mosaic"?

• A. Its proteins never move
• B. It is a rigid wall of cellulose
• C. It is made of liquid water
• D. Phospholipids move freely and proteins are scattered through them like tiles

Question 5

A cladogram branches in this order (first branch = most distantly related): moss, fern, pine, sunflower. Which of these options is most closely related to the pine?

• A. fern
• B. sunflower
• C. moss

Question 6

Allele frequencies in a population change over generations. What does this show?

• A. The population is extinct
• B. The population is evolving
• C. Hardy–Weinberg equilibrium
• D. No mutations ever happen

Question 7

Assuming the genes are on different chromosomes, how many different kinds of gamete can an organism with genotype Aa make?

Answer 

Question 8

Which evidence is now used most to build evolutionary trees?

• A. comparing body size only
• B. comparing where animals live
• C. comparing DNA and protein sequences
• D. comparing colours

Question 9

Membranes: which statement is true?

• A. The cell membrane is a phospholipid bilayer with proteins in it.
• B. Phospholipid tails are attracted to water.
• C. Facilitated diffusion moves substances against their gradient.
• D. Large proteins pass through the membrane by simple diffusion.

Question 10

In a sample of double-stranded DNA, 28 % of the bases are adenine (A). What percentage are guanine (G)?

Answer %

Question 11

Two pea plants, both RrYy (round, yellow seeds), are crossed. They produce 160 seeds. How many would you expect to be round and green (one dominant, one recessive)?

Answer 

Question 12

A guinea pig with genotype BbRr is crossed with one that is bbrr. What ratio of phenotypes is expected in the offspring?

• A. 9 : 3 : 3 : 1
• B. 1 : 1 : 1 : 1
• C. 3 : 1
• D. 1 : 1

Question 13

In a population, 36 % of individuals show a recessive phenotype (aa). Assuming Hardy–Weinberg equilibrium, what is the frequency of the recessive allele, q?

Answer 

Question 14

A double-stranded DNA fragment has 2000 bases in total. 500 of them are cytosine. How many are adenine?

Answer 

Question 15

The frequency of a recessive allele in a population is q = 0.3. What percentage of the population are expected to be heterozygous carriers (2pq)?

Answer %

Question 16

A cladogram branches in this order: moss, fern, pine, sunflower. New traits: vascular tissue appears before the fern branch; seeds appears before the pine branch; flowers appears before the sunflower branch. Does the sunflower have vascular tissue?

• A. yes
• B. no