Question

directions: read and annotate all questions. answer all questions.

1. which example describes an adaptation that aids survival?

(1) the height of a giraffe enables it to feed on the leaves of trees that other animals cannot reach.
(2) a finchs beak size makes it difficult for the finch to break apart large seeds.
(3) a white peppered moth is clearly visible against the background of a dark - colored tree.
(4) the broad leaves of a maple tree shrivel up when placed in the hot climate of a desert.

1. according to modern evolutionary theory, alleles responsible for new traits that help a species survive in a particular environment will usually

(1) not change in frequency
(2) decrease rapidly in frequency
(3) decrease gradually in frequency
(4) increase in frequency

1. which of these best defines the term adaptation?

(1) a gene that increases the rate of reproduction in a species
(2) a trait that gives an organism a survival or reproductive advantage
(3) a characteristic that lowers an organisms chances of passing on its genes
(4) a mutation that has a neutral effect on an organisms chances of survival

1. a scientist is studying allele frequencies in a population of animals. at the beginning of the study, the b allele makes up 50 percent of the alleles for this trait. after a period of time, the b allele makes up 70 percent of the alleles for this trait. the b allele most likely corresponds to a trait that

(1) has no impact on survival
(2) has little impact on reproduction
(3) is beneficial in this environment
(4) is harmful in this environment

1. in an area in africa, temporary pools form where rivers flow during the rainy months. some fish have developed the ability to use their ventral fins as “feet” to travel on land from one of these temporary pools to another. other fish in these pools die when the pools dry up. what can be expected to happen in this area after many years?

(1) the fish using ventral fins as “feet” will be present in increasing numbers.
(2) the fish using ventral fins as “feet” will develop real feet.
(3) the “feet,” in the form of ventral fins, will develop on all fish.
(4) all of the varieties of fish will survive and produce many offspring.
base your answer to question 6 on information in the following table and on your knowledge of the process of evolution.

habitat	number of toes	type of horse species
forest	four toes	ancestral horse (eohippus)

1. you could hypothesize that modern horses have fewer toes than ancestral horse species had because the

(1) changed habitat wore down their si toes as they ran fast over the plains
(2) ancestral horse species mated with several mutant one - toed horses
(3) people who first rode them prefer horses that had one large hoof per
(4) changed habitat favored survival of faster horses that had reduced toes

Explanation:

1. Question 1: The height of a giraffe allowing it to feed on leaves other animals can't reach is an adaptation for survival as it gives the giraffe access to a unique food - source. A finch's beak not being able to break large seeds is not a survival - aiding adaptation. A white peppered moth being visible against a dark - colored tree is a disadvantage, not an adaptation. A maple tree's leaves shriveling in a desert is not an adaptation but a negative response to the environment.
2. Question 2: According to modern evolutionary theory, alleles responsible for new traits that help a species survive in a particular environment will increase in frequency as those with the beneficial alleles are more likely to survive and reproduce.
3. Question 3: Adaptation is a trait that gives an organism a survival or reproductive advantage. It is not just a gene for increased reproduction, nor a characteristic that lowers an organism's chance of passing on genes, nor a neutral - effect mutation.
4. Question 4: Since the frequency of the B allele increased from 50% to 70%, it most likely corresponds to a trait that is beneficial in this environment as beneficial traits tend to increase in frequency over time due to natural selection.
5. Question 5: The fish using ventral fins as "feet" will be present in increasing numbers because they have an adaptation that allows them to move between pools when other fish die due to pool drying. Developing real feet is not a short - term outcome, and not all fish will develop this trait, and not all fish varieties will survive.
6. Question 6: Modern horses have fewer toes than ancestral horse species because the changed habitat (plains) favored the survival of faster horses that had reduced toes. Wearing down of toes is not the main evolutionary reason, and mating with mutant one - toed horses is not the most likely explanation, and human preference is not an evolutionary factor in the wild.

Answer:

1. (1)
2. (4)
3. (2)
4. (3)
5. (1)
6. (4)