Bacteria reproduce asexually, whereas most plants and animals reproduce sexually. Which is the
better method?
a.
Neither method is better—each is effective in different environments for different kinds of
organisms.
b.
Sexual reproduction is the better method, because it produces more variation.
c.
Sexual reproduction is the better method, because more plants and animals than bacteria are
present.
d.
Asexual reproduction is the better method, because more bacteria than plants and animals are
present.
e.
Asexual reproduction is better, because binary fission is more efficient. - Answers a.
Neither method is better—each is effective in different environments for different kinds of
organisms.
Some genes, such as the human ABO blood groups, have more than two alleles. For these
genes:
a.
some individuals can be triply heterozygous.
b.
natural selection cannot alter the allele frequencies.
c.
,a greater proportion of the individuals must be heterozygous than homozygous.
d.
normal dominance relationships are not possible.
e.
individuals can only possess two alleles. - Answers e.
individuals can only possess two alleles.
In the case of Mendel's peas, a single gene determined the height of the plant; however, in
humans, adult height is influenced by many genes. A trait such as human height is said to be:
a.
codominant.
b.
polygenic.
c.
multi-allelic.
d.
incompletely dominant.
e.
pleiotropic. - Answers b.
polygenic
Phenotypes are generally a product of:
a.
two or more genes in combination with each other.
b.
the genotype.
,c.
the environment.
d.
multiple alleles at the same gene locus.
e.
the genotype in combination with the environment. - Answers e.
the genotype in combination with the environment.
Flower color in snapdragons is an example of incomplete dominance. When a red-flowered
plant is crossed with a white-flowered plant, the offspring have pink flowers. If a pink-flowered
plant is crossed with another pink-flowered plant, their offspring will be:
a.
all red.
b.
25% white and 75% red.
c.
25% red, 50% pink, and 25% white.
d.
50% pink and 50% red.
e.
all pink. - Answers c.
25% red, 50% pink, and 25% white.
When crossing-over occurs, _______________ genes usually stay together.
a.
multi-allelic
, b.
sex-linked
c.
pleiotropic
d.
independently assorting
e.
linked - Answers e.
linked
Albinism (lack of skin and hair pigmentation) is caused by a recessive autosomal allele. A
woman and man, both normally pigmented, have an albino child together. For this trait, what is
the genotype of the albino child?
a.
heterozygous
b.
homozygous recessive
c.
homozygous dominant
d.
It is unknown, because not enough information is provided.
e.
It depends on the sex of the child. - Answers b.
homozygous recessive
A true-breeding red rose is repeatedly mated with a true-breeding white rose, and all of their
offspring are red. If two of these red offspring are mated, what percentage of their offspring will
be red?