12th grade cells, genetics and evolution

Example

Two pea plants, both RrYy (round, yellow seeds), are crossed. They produce 16 seeds. How many would you expect to be round and yellow (both dominant traits)?

1. 16 ÷ 16 = 1
2. 1 × 9 = 9
3. So the answer is: 9

Answer: 9

Example

In a population, 49 % of individuals show a recessive phenotype (aa). Assuming Hardy–Weinberg equilibrium, what is the frequency of the recessive allele, q?

1. q² = 0.49
2. q = √0.49 = 0.7
3. So the answer is: 0.7

Answer: 0.7

Example

In a sample of double-stranded DNA, 30 % of the bases are adenine (A). What percentage are guanine (G)?

1. A = T = 30 %, so A + T = 60 %
2. 100 − 60 = 40
3. 40 ÷ 2 = 20
4. So the answer is: 20 %

Answer: 20 %

Example

Is this passive or active transport: a gland cell releasing hormone in vesicles (exocytosis)?

1. Active transport and bulk transport use energy from ATP.
2. So the answer is: active (uses ATP)

Answer: active (uses ATP)

Example

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 shark have four limbs?

1. four limbs appears after the shark branches off, so it lacks it.
2. So the answer is: no

Answer: no