Focusvragen Inleiding in de Psychologie H3 - H15
Ch. 3 Genetics and Evolutionary Foundations of
Behavior
1. How can genes affect behavioral traits through their role in protein synthesis?
All effects that genes have on behavior occur through their role in building and modifying in
physical structures of the body.
Genes might influence some behavior by promoting the development of any system in the
body.
2. What does it mean to say that genes can influence behavioral traits only through interaction
with the environment (1)? How are genes involved in long-term behavioral changes derived
from experience (2)?
Environmental effects help turn genes on and off, resulting in bodily changes that alter the
individual’s behavioral capacity (1). Experiences activate genes, which produces proteins,
which in turn alter the function of some of the neural circuits in the brain and thereby
change the individual’s behavior (2).
3. How can the same genotype produce various phenotypes?
Because of differences in the environments in which the genotypes are.
4. How does meiosis produce egg or sperm cells that are all genetically different from one
another?
During meiosis, the pairs of replicated chromosomes line up next to one another and
exchange genetic material through a process called crossing over, and then the cell divides
twice; each cell is genetically different.
5. What is the advantage of producing genetically diverse offspring?
Genes have better a better chance of surviving if they are rearranged at each generation in
many ways, than if they are all put into the same kind of body.
6. What is the difference between a dominant and a recessive gene (or allele)?
A dominant gene will produce its observable effects in either the homozygous or the
heterozygous condition, and a recessive gene will only produce its observable effects in the
homozygous condition.
7. Why do three-fourths of the offspring of two heterozygous parents show the dominant trait
and one-fourth show the recessive trait?
There is always one allele from each parent. Because there are four alleles in total that way,
there are four possibilities for the child’s alleles. The four possibilities will show that there is
one dominant homozygous (AA), two heterozygous (Aa) and one recessive homozygous (aa);
3:1 ratio.
8. Why might a disease caused by two recessive genes persist in the gene pool?
Although having two recessive genes was often a death sentence/could cause a disease,
having just one recessive and one dominant gene, could provide some benefit under specific
circumstances.
9. …
During the mating process with both the fearful and the fearless dogs, it seemed that the
ratio was 3:1, which shows that the single gene locus with the fear allele dominant was.
10. Why would it be a mistake to conclude that fear in dogs is caused just by one gene or that it
is caused just by gene and not by the environment?
If raised under a different environment, the dogs could react very different; either more
fearful or less.
,Focusvragen Inleiding in de Psychologie H3 - H15
11. How do genes and the environment interact to affect individuals with PKU?
When people with PKU don’t consumes foods that contain phenylalanine when they are
babies, they develop normally and later-on, when they are grownup, can consume
phenylalanine without any negative consequences.
12. How does the distribution of scores for a polygenic trait differ from that usually obtained for
a single-gene trait?
The measures taken from individuals do not fall into two or more distinct groups but can lie
anywhere within the observed range of scores; the most scores fall near the middle of the
range and the frequency tapers off toward the two extremes.
13. How are the characteristics of animals shaped through selective breeding?
This procedure involves the mating of individuals that lei toward the same extreme on the
measure in question.
14. How did Tyron produce maze bright and maze dull strains of rats (1)? How did he show that
the difference was the result of genes, not rearing (2)?
By mating the smart rats with smart rats (and same with the dull rats) (1). He cross-fostered
the rats; the rats were raised by mothers in the other strains (2).
15. Why is the strain difference produced by Tyron not properly characterized in terms of
brightness or dullness?
All he had measured was their performance in a maze.
16. How might a better understanding of epigenetics change the way we view genetic
inheritance?
We inherit a variety of chemical markers that regulate genes (turning them off or on); not
only DNA and determining how much protein they produce.
17. What insight led Darwin to his theory of evolution (1)? How is natural selection like and
different from artificial selection (2)?
Breeding in nature is selective and can produce changes in living things over generations (1).
Similar: there are changes in living things, different: artificial is human-controlled and natural
is a result of obstacles to survival and reproduction (2).
18. How are genes involved in evolution (1)? What are the sources of genetic diversity on which
natural selection acts?
Genes that improve an individual’s ability to survive and reproduce in the existing
environment increase from generation to generation, and genes that impede this ability
decrease (1). The reshuffling of genes that occurs in sexual reproduction and mutations in
the genes (2).
19. How does the change in the environment affect the direction and speed of evolution (1)?
How did a study of finches illustrate the role of environmental change in evolution (2)?
Environmental change spurs evolution not by causing the appropriate mutations to occur,
but by promoting natural selection (1). The thickness of the beaks of the finches where
somewhat different after environmental changes; thicker, more powerful beaks were
positive in the environment, so those genes were passed on more (2).
20. What are the three mistaken beliefs about evolution, all related to the misconception that
foresight is involved?
Evolution could produce changes for some future purpose, even though they are useless or
harmful at the time that the change occurs (1), present-day organisms can be ranked
according to the distance they have moved along a set evolutionary route, toward some
, Focusvragen Inleiding in de Psychologie H3 - H15
planned end (2) and the idea that natural selection is a moral force, that its operation and its
products are in some sense right or good.
21. How does an understanding of evolution provide a basis for functionalism in psychology?
Functionalism tries to explain behavior in terms of what it accomplishes for the behaving
individual (which trait helped ancestral members of the species to survive and reproduce).
22. How are distal explanations of behavior different from, but complementary to, proximate
explanations?
Distal are explanations at the evolutionary level; the role that the behavior has played in the
animal’s survival and reproduction over evolutionary time. Proximate are explanations that
deal not with function but with mechanism: statements of the immediate conditions that
elicit the behavior.
23. What are four reasons for the existence of traits or behavior that do not serve survival and
reproductive functions?
They are vestigial characteristics; they served the needs of the ancestors and are no longer
functional today, yet they remain (1), they are side effects, by-products, of natural selection
for other, useful changes (2), some inheritable characteristics that result from just one or two
mutations are inconsequential for survival and reproduction (3) and even evolved
mechanisms, such as that for emotion, drive or tendency, are not useful in every situation in
which they are active (4).
24. What evidence supports the idea that many human emotional expressions are examples of
species-typical behaviors?
The expressions are universal, occurring in people throughout the world and even in people
who were born blind and thus could not have learned them through observation.
25. How do human emotional expressions illustrate the point that species-typical behaviors can
be modified by learning?
We can control and modify our emotional expressions and learn new ones. The explanation
of this, is the fact that there are cross-cultural differences throughout the world.
26. How do the examples of two-legged walking and language in humans, and singing in white-
crowned sparrows, illustrate the point that species-typical behaviors may depend on
learning?
The development of such things as walking, talking (humans) and singing (crows), clearly
depends on learning. If humans or crows were raised in an environment where species-
typical behavior was impossible to practice, they would not develop that behavior.
27. How is the concept of biological preparedness related to that of species-typical behavior (1)?
How do the examples of human walking and talking illustrate biological preparedness (2)?
Species-typical behaviors depend on biological preparedness; having anatomical structures
that permit and motivate that behavior (1), like having legs to learn to walk and having a
mouth and ability to talk (2).
28. Why is the concept of species-typical behavior relative rather than absolute?
No behavior stems just from biological preparedness; some sort of experience with the
environment is always involved. Conversely, any behavior that an individual can produce
must make use of the individual’s inherited biological capacities.
29. What is the difference between a homology and an analogy, and how can researchers tell
whether a similarity between two species in some trait is one or the other?
Homology is any similarity that exists because of the different species’ common ancestry.
Analogy is any similarity that stems not form common ancestry but from convergent
evolution; it occurs when different species independently evolve a common characteristic.
