12th grade cells, genetics and evolution

Question 1

In a sample of double-stranded DNA, 24 % of the bases are thymine (T). What percentage are cytosine (C)?

Answer %

Question 2

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

Answer 

Question 3

The frequency of a recessive allele in a population is q = 0.4. What percentage of the population are expected to be heterozygous carriers (2pq)?

Answer %

Question 4

Modern classification groups organisms into three domains. Which list is correct?

• A. Vertebrates, Invertebrates, Plants
• B. Prokaryotes, Protists, Viruses
• C. Archaea, Bacteria, Eukarya
• D. Plants, Animals, Fungi

Question 5

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

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

Question 6

Two pea plants, both RrYy (round, yellow seeds), are crossed. They produce 80 seeds. How many would you expect to be wrinkled and green (both recessive traits)?

Answer 

Question 7

A sample has 21 % A, 29 % T, 25 % C and 25 % G. What does this suggest?

• A. It must be RNA because it contains T
• B. It is likely single-stranded DNA, because A ≠ T
• C. The measurements prove an error in all DNA
• D. It is normal double-stranded DNA

Question 8

Why can oxygen cross the membrane easily but glucose needs a protein?

• A. Oxygen is too big for proteins
• B. Oxygen is small and non-polar; glucose is larger and polar
• C. Glucose is a gas
• D. Glucose dissolves in fat

Question 9

In p² + 2pq + q² = 1, what does p² represent?

• A. the frequency of carriers
• B. the frequency of homozygous dominant individuals
• C. the frequency of recessive individuals
• D. the frequency of the dominant allele

Question 10

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 sunflower?

• A. moss
• B. pine
• C. fern

Question 11

A double-stranded DNA fragment has 400 bases in total. 100 of them are cytosine. How many are adenine?

Answer 

Question 12

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 fern have vascular tissue?

• A. yes
• B. no

Question 13

Membranes: which statement is true?

• A. Facilitated diffusion uses carrier or channel proteins but no ATP.
• B. Facilitated diffusion moves substances against their gradient.
• C. Phospholipid tails are attracted to water.
• D. Large proteins pass through the membrane by simple diffusion.

Question 14

In a population, 4 % of individuals show a recessive phenotype (aa). Assuming Hardy–Weinberg equilibrium, what is the frequency of the recessive allele, q?

Answer 

Question 15

Two guinea pigs, both Bb (black fur, B dominant), are crossed. What ratio of black to white offspring is expected?

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

Question 16

In a sample of double-stranded DNA, 34 % of the bases are thymine (T). What percentage are cytosine (C)?

Answer %