Genetics Exam 3/21

Which statement describes genetic engineering?

• It changes the genes contained in hereditary material.

• It provides energy for cell division.

• It is necessary for the normal formation of sex cells.

• It reduces variation in organisms that reproduce asexually.

According to the gene-chromosome theory, which statement is true?

• Genes are present only on the chromosomes of humans.

• Genes are arranged in a linear sequence on a chromosome

• Genes are located only on sex chromosomes.

• Mutations occur mainly in body cells.

The kind of genes an organism possesses is dependent upon the

• type of proteins in the organism’s nuclei

• sequence of bases in the organism’s DNA

• number of ribosomes in the organism’s cytoplasm

• size of the mitochondria in the organism’s cells

Random separation and distribution of homologous chromosomes occurs during

• cleavage

• mitotic cell division

• fertilization

• meiotic cell division

Scientists have cloned sheep but have not yet cloned a human. The best explanation for this situation is that

• the technology to clone humans has not been explored

• human reproduction is very different from that of other mammals

• there are many ethical problems involved in cloning humans

• cloning humans would take too long

Mutations usually:

• are caused only by the events of cell division

• do not occur at random

• result in changes in DNA

• occur to meet the needs of a species

In screech owls, red feathers are dominant over gray feathers. If two heterozygous red-feathered owls are mated, what percentage of their offspring would be expected to have red feathers?

• 25%

• 50%

• 75%

• 100%

New inheritable characteristics would be least likely to result from

• mutations which occur in muscle cells and skin cells

• mutations which occur in male gametes

• mutations which occur in female gametes

• the sorting and recombination of existing genes during meiosis and fertilization

If the pattern of inheritance for a trait is complete dominance, then an organism heterozygous for the trait would normally express

• the recessive trait, only

• the dominant trait, only

• a blend of the recessive and dominate traits

• a phenotype unlike that of either parent

A change in the base sequence of DNA is known as

• a gene mutation

• a karyotype

• nondisjunction

• polyploidy