AnswersCR03051B BiologyUnit Test

Factors Affecting Genetic Variation Answers

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1
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The map shows the allele frequency of sickled hemoglobin (HbS) and malaria endemicity in Africa. Which statement best explains the relationship between HbS allele frequency and malaria endemicity in Africa?

Question illustration
A
When an area is malaria free, the HbS allele frequency is between 0 and 4.04.
B
When an area is holoendemic, the HbS allele frequency is between 0.52 and 4.04.
C
When an area is malaria free, the HbS allele frequency is between 12.64 and 18.18.
D
When an area is holoendemic, the HbS allele frequency is between 0 and 0.51.
2
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In terms of natural selection, what is the best description of an organism that is fit?

A
The organism is physically stronger than competing organisms.
B
The organism is physically stronger than organisms of a different species.
C
The organism is better able to survive and pass on traits to offspring than competing organisms.
D
The organism is a member of a population in which every member survives without competing.
3

A frog has more offspring than can survive on available resources.Of which is this an example?

A
structural adaptation
B
overpopulation
C
variation in a population
D
artificial selection
4

Which statement describes natural selection?

A
It is the primary mechanism for evolution.
B
It must act on structural traits.
C
It acts to cause overpopulation.
D
It causes learned skills to become heritable traits.
5

Koalas are marsupials that are found in eastern Australia. Although their ancestors lived mostly on the ground, modern koalas spend most of their time in eucalyptus trees. This is possible because their hands and feet have strong claws and opposable digits.What other adaptation could have helped koalas as they evolved from land dwellers to tree dwellers?

Question illustration
A
the ability to have several offspring at one time
B
fur color that closely matches the eucalyptus bark color
C
longer hind legs that allow for faster running
D
better ability to communicate with their peers
6

Which was Charles Darwin’s contribution to the study of biology?

A
He was the first person to recognize that organisms change over time.
B
He believed that organisms adapted through the inheritance of acquired traits.
C
He explained how traits are passed from parents to offspring.
D
He proposed that natural selection is the primary mechanism of evolution.
7

According to the concept of “survival of the fittest," if a population of birds eats worms that they find deep under ground by using their beaks, which members of the bird population would be more fit?

A
birds that have flatter beaks
B
birds that have longer beaks
C
birds that have wider beaks
D
birds that have brighter beaks
8

Which statement would least likely be used to describe variation?

A
Variations are inherited differences between individuals of the same species.
B
Variations that decrease reproductive success are more likely to be passed on.
C
Variations may result in changes to an entire population after many generations.
D
Variations provide some individuals with an advantage.
9

Natural selection is a process by which organisms that are better adapted to their environment tend to

A
increase in size.
B
migrate.
C
evolve new traits.
D
survive.
10

Consider this image of a gazelle.Which of the gazelle’s naturally selected traits is shown in this picture to be an evolutionary advantage?

Question illustration
A
feeding only at certain times of the day
B
coat color for blending in with dry grass
C
specialized gut due to a diet of grasses
D
specific gender roles to diminish predation
11

Which would least likely be a cause of natural selection?

A
adaptation
B
evolution
C
overpopulation
D
variation
12

Veronica wrote Charles Darwin’s main points on the board, but she made a mistake in one point.1. Since more offspring are produced than an environment can support, organisms within a population must compete for resources to survive.2. Due to variations within the population, some competitors will be better equipped for survival than others.3. The best-equipped organisms will survive and will produce well-equipped offspring. 4. Variations that help with survival will be passed on to future generations and will rapidly change the whole population.Which point is flawed as written above?

A
point 1
B
point 2
C
point 3
D
point 4
13

What is natural selection?

A
a process that selects variations that help with survival and that spreads the variations to more offspring
B
a process through which nature selects an individual within a population for extinction
C
a process that causes all populations to gradually increase in size
D
a process that causes random variations to appear in the offspring of every generation
14

During a trip to the Galapagos Islands, which observation led Charles Darwin to suspect that organisms change over time?

A
Island finches were able to breed with mainland species.
B
Island finches resembled mainland finches, but were not the same species.
C
Island finches resembled extinct species from other islands around the world.
D
Island finches did not have beaks of the same size and shape.
15

Charles Darwin observed a unique beak size and shape in the finch population of each of the Galapagos Islands that he visited. Which is the most likely cause of the observed variation?

Question illustration
A
differences in the climate among the islands
B
competition among individuals for available food sources
C
competition among individuals for desirable mates
D
differences in egg size among the populations
16

Which organism exhibits behavioral adaptation?

A
an owl with large pupils and eyes that enable it to see better at night
B
a possum playing dead to increase its chances of survival
C
an insect that mimics its environment to hide from its predators
D
a desert plant that sheds its leaves to lessen water loss during the dry season

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