Biology Answer Scheme SB025
3: SELECTION AND SPECIATION
3: SELECTION AND SPECIATION
OBJECTIVE QUESTIONS
1. Stabilizing selection occurs when selection
A. acts against rare individuals.
B. acts against both extreme phenotypes.
C. completely removes a trait from a population.
D. favor both extremes of the phenotypic range.
2. Only of a few types of particular bird species diverge after a small colonizes a new
PR
island. This mechanism is called
A. stabilizing selection C. the Founder effect
B. directional selection D. disruptive selection
O
3. Which statement is TRUE about allopatric speciation?
A. Speciation produces hybrid species.
FD
B. Individuals occupy an overlapping area.
C. Speciation is not caused by geographical factors.
D. Geographical barriers prevent gene flow between populations.
O
4. Very similar species of fish release their eggs and sperms into the same water, but the
sperms of one species cannot penetrate the eggs of another species. This is an example of
pre-zygotic isolation by
C
A. ecological isolation C. gametic isolation
B. behavioral isolation D. mechanical isolation
5. The effectiveness of geographical barriers in promoting speciation is related to
A. size of barrier.
B. size of the population it separate.
C. speed at which the barrier form.
D. ability of organism to overcome the barrier.
, Biology Answer Scheme SB025
3: SELECTION AND SPECIATION
6. What prevents horses and donkeys from hybridizing to form a new species?
A. Gametic isolation C. Reduced hybrid viability
B. Behavioral isolation D. Reduced hybrid fertility
7. Which of the following are examples of adaptive radiation?
I. Marsupial mammals in Australia.
II. Beak shapes of Darwin’s finches in Galapagos island.
III. Melanic peppered moths in England during Industrial revolution.
A. I only C. II and III only
PR
B. I and II only D. I, II and III
8. Three selection processes are given below. Match the process given with the correct type
of selection method.
I. Selection of heterozygotes individuals for sickle-cell anaemia in areas where
O
malaria is endemic.
II. Increase in insecticide resistant pests.
III. Formation of two subpopulations of grass: toxic-tolerant and non-tolerant grasses.
FD
Stabilizing selection Directional selection Disruptive selection
A. III II I
B. I III II
O
C. I II III
D. II III I
C
9. Due to fluctuations in the environment, a population may periodically experience a rapid
decrease in the number of individuals. When this occurs, genetic drift can occur in the few
remaining survivors, a process referred to as
A. migration C. bottleneck effect
B. founder effect D. gene flow
10. Reproductive isolation mechanisms that prevent fertilization are termed as
A. post-zygotic barriers C. biological barriers
B. pre-zygotic barriers D. zygotic barriers
, Biology Answer Scheme SB025
3: SELECTION AND SPECIATION
11. The hawthorn and apple maggot flies appear to have become reproductively isolated from
each other largely because
A. they have different mating behaviors.
B. they occupy different parts of the habitat.
C. they have adapted to two different hosts.
D. they mate at different times of the day.
STRUCTURED AND ESSAY QUESTIONS
3.1 SELECTION
PR
1. FIGURE 1 shows graphs representing THREE types of natural selection. The arrows
indicate selection pressures.
O
FD
O
FIGURE 1
C
(a) State the types of selection in I, II and III. [3 marks]
I: directional (selection)
II: disruptive (selection)
III: stabilizing (selection)
(b) Name ONE example for each type of selection. [3 marks]
I: industrial melanism / Biston betularia / black peppered moth / beak
sizes of Galapagos finches // body sizes of black bears // body size of
guppy // big-horn sheep / ram
II: variety of beak sizes and shapes of Galapagos / Cameroon finches //
polymorphism
III: human birth weight // wing length of hawk / eagle
3: SELECTION AND SPECIATION
3: SELECTION AND SPECIATION
OBJECTIVE QUESTIONS
1. Stabilizing selection occurs when selection
A. acts against rare individuals.
B. acts against both extreme phenotypes.
C. completely removes a trait from a population.
D. favor both extremes of the phenotypic range.
2. Only of a few types of particular bird species diverge after a small colonizes a new
PR
island. This mechanism is called
A. stabilizing selection C. the Founder effect
B. directional selection D. disruptive selection
O
3. Which statement is TRUE about allopatric speciation?
A. Speciation produces hybrid species.
FD
B. Individuals occupy an overlapping area.
C. Speciation is not caused by geographical factors.
D. Geographical barriers prevent gene flow between populations.
O
4. Very similar species of fish release their eggs and sperms into the same water, but the
sperms of one species cannot penetrate the eggs of another species. This is an example of
pre-zygotic isolation by
C
A. ecological isolation C. gametic isolation
B. behavioral isolation D. mechanical isolation
5. The effectiveness of geographical barriers in promoting speciation is related to
A. size of barrier.
B. size of the population it separate.
C. speed at which the barrier form.
D. ability of organism to overcome the barrier.
, Biology Answer Scheme SB025
3: SELECTION AND SPECIATION
6. What prevents horses and donkeys from hybridizing to form a new species?
A. Gametic isolation C. Reduced hybrid viability
B. Behavioral isolation D. Reduced hybrid fertility
7. Which of the following are examples of adaptive radiation?
I. Marsupial mammals in Australia.
II. Beak shapes of Darwin’s finches in Galapagos island.
III. Melanic peppered moths in England during Industrial revolution.
A. I only C. II and III only
PR
B. I and II only D. I, II and III
8. Three selection processes are given below. Match the process given with the correct type
of selection method.
I. Selection of heterozygotes individuals for sickle-cell anaemia in areas where
O
malaria is endemic.
II. Increase in insecticide resistant pests.
III. Formation of two subpopulations of grass: toxic-tolerant and non-tolerant grasses.
FD
Stabilizing selection Directional selection Disruptive selection
A. III II I
B. I III II
O
C. I II III
D. II III I
C
9. Due to fluctuations in the environment, a population may periodically experience a rapid
decrease in the number of individuals. When this occurs, genetic drift can occur in the few
remaining survivors, a process referred to as
A. migration C. bottleneck effect
B. founder effect D. gene flow
10. Reproductive isolation mechanisms that prevent fertilization are termed as
A. post-zygotic barriers C. biological barriers
B. pre-zygotic barriers D. zygotic barriers
, Biology Answer Scheme SB025
3: SELECTION AND SPECIATION
11. The hawthorn and apple maggot flies appear to have become reproductively isolated from
each other largely because
A. they have different mating behaviors.
B. they occupy different parts of the habitat.
C. they have adapted to two different hosts.
D. they mate at different times of the day.
STRUCTURED AND ESSAY QUESTIONS
3.1 SELECTION
PR
1. FIGURE 1 shows graphs representing THREE types of natural selection. The arrows
indicate selection pressures.
O
FD
O
FIGURE 1
C
(a) State the types of selection in I, II and III. [3 marks]
I: directional (selection)
II: disruptive (selection)
III: stabilizing (selection)
(b) Name ONE example for each type of selection. [3 marks]
I: industrial melanism / Biston betularia / black peppered moth / beak
sizes of Galapagos finches // body sizes of black bears // body size of
guppy // big-horn sheep / ram
II: variety of beak sizes and shapes of Galapagos / Cameroon finches //
polymorphism
III: human birth weight // wing length of hawk / eagle
