Biology STAR Benchmark Test

1. If a corn plant has a genotype of Ttyy, what are the possible genetic combinations that could be present in a single grain of pollen from this plant?

a. Ty,ty

b. TY,ty

c. Ty, TY

d. tY, Ty

2. The table below list the typical diploid number of chromosomes of several different organisms. Which of the following is the best explanation for why the chromosome number is an even number in each of these organisms?

Goldfish	94
Potato	48
Human	46
Pea	14
Fruit fly	8

a. It is the only coincidence; many other organisms have an odd number of chromosomes.

b. The diploid chromosome number is always even to that when mitosis occurs each new cell get the same number of chromosomes.

c. The diploid number represents pairs of chromosome, one from each parent, so it is always an even number.

d. Chromosomes double every time the cell divides, so after the first division, the number is always even.

3. Which of the following sequences represents chromosome numbers during fertilization?

a. n + n -> 2n

b. 2n -> n + n

c. n -> n

d. 2n -> 2n

4. In fruit flies, the gene for red eyes is (R) dominant and the gene for sepia eyes (r) is recessive. What are the combinations of genes in the offspring of two red-eyed heterozygous flies (Rr)?

a. RR

b. Rr

c. Rr and rr

d. RR, Rr and rr

5. In a certain breed of dogs, deafness is due to a recessive allele (d) of a particular gene, and normal hearing is due to its dominant allele (D). What percentage of the offspring of a normal heterozygous (Dd) dog and a deaf dog (dd) would be expected to have normal hearing?

a. 0%

b. 25%

c. 50%

d. 100%

5' ATCAGCGCTGGC 3'

6. The above sequence of DNA is part of a gene. How many amino acids are coded for by this segment?

a. 4

b. 8

c. 12

d. 20

7. Which of these would most likely cause a mutation?

a. The placement of ribosomes on the endoplasmic reticulum

b. The insertion of a nucleotide into DNA

c. The movement of transfer RNA out of the nucleus

d. The release of messenger RNA from DNA

8. A base sequence is as follows: ACAGTGC How would the sequence be coded on mRNA

a. TGTCACG

b. GUGACAU

c. UGUCACG

d. CACUGUA

9. One human disease is caused by a change in one codon from GAA to GUA. This disease is a result of a

a. A mutation

b. A meiosis error

c. Crossing over

d. Polyploidy

10. Genetic engineering has produced goats whose milk contains proteins that can be used as medicines. This effect was produced by

a. Mixing foreign genes into the milk

b. Injecting foreign genes into the goats’ udders

c. Inserting foreign genes into the fertilized egg

d. Genetically modifying the nutritional needs of the goats’ offspring

Answer Key

1. A

2. C

3. A

4. D

5. C

6. A

7. B

8. C

9. A

10. C

a.