Biology 182: Exam 2: Modules 3-4

Which of the following environmental factors can affect the phenotypes expressed by a genotype?

Atmospheric oxygen, diet, solar radiation, and humidity

What causes genetic drift?

Independent assortment of alleles, random variation in survival/mating success/offspring, and any chance event that prevents you from passing on your allele from one generation to the next

When biologists use an optimality model to predict foraging behavior, they assume that animals behave in a way that ___________?

Maximizes energy gained over time

Which type of chemical bond will stabilize an enzyme's structure the most?

Covalent

Modes of Selection

Describe how the distribution shifts over generations: stabilizing selection, directional selection, and disruptive selection

Which type of organisms should evolve the most rigid enzymes?

Desert organisms

An organism that invests more energy in reproduction will likely ____________.

Die earlier

The fact that one can find fish in both tropical and polar waters implies that ____________.

Different species of fish have adapted to different environmental conditions

Asexually

Directs cells to divide and develop into new tissues and organs

True or False? Acclimation involves a change in the genotype triggered by a change in the environment.

False. Acclimation involves a change in the phenotype with a change in the environment.

True or False? Stabilizing selection occurs more often than disruptive selection.

False. All the of these forms of selection can happen.

True or False? All individuals of a species express the same degree of plasticity.

False. Each species expresses their own degree of plasticity needed.

True or False? Genetic drift cannot eliminate a beneficial allele from a population.

False. Genetic drift can eliminate beneficial alleles from a population.

True or False? Genetic drift cannot eliminate beneficial alleles.

False. Genetic drift can eliminate beneficial alleles in small populations.

True or False? On average, genetic drift will increase the frequency of a deleterious allele.

False. Genetic drift can increase the frequency of a deleterious allele or a beneficial allele based on chance.

True or False? Acclimation benefits an organism the most when the environment changes quickly and the phenotype changes slowly.

False. It benefits an organism the most when the environment changes slowly and the phenotype changes instantly.

True or False? To maximize its energy gain, the bird should remain on one tree.

False. It depends on the net benefit. If the bird can get more energy from another tree, the bird should leave.

True or False? The longer the light remained lit, the greater the cost of thermoregulation.

False. It would be less cost because less energy is used to move back and forth.

True or False? If a mutation occurred, causing the daughter of two pygmies to grow taller than usual, this daughter would likely reproduce at an even earlier age than her parents did.

False. She would reproduce later as it takes longer for her to mature.

True or False? Most organisms grow as much as possible throughout their lives.

False. Some populations must mature quicker.

True or False? On cloudy days, neither species thermoregulated, likely because solar radiation was absent.

False. Species can only thermoregulate when there is solar radiation.

True or False? An enzyme maintains a rigid structure while catalyzing a reaction.

False. The enzyme stretches to fit like a glove.

True or False? The net benefit equals the benefit divided by the cost.

False. The net benefit is the the benefit minus cost.

True or False? If the slope of the relationship between the phenotype and fitness is positive, natural selection would decrease the phenotype over generations.

False. The positive relationship would lead to an increase in the phenotype over generations.

True or False? Genetic drift cannot occur in the same generation as natural selection.

False. They can occur in the same generation known as the drift-selection balance.

True or False? African pygmies are likely to reproduce earlier because they lack sufficient food to continue growing.

False. They stop growing because they had to start reproducing earlier.

Phenotypic plasticity occurs when one __________ produces multiple __________.

Genotype, phenotypes

Catabolism

Metabolic pathways that break down molecules, releasing energy

Anabolism

Metabolic pathways that construct molecules, requiring energy

The optimal strategy maximizes the ___________.

Net benefit

The range of environmental temperatures in which a genotype can persist is one aspect of its _________.

Niche

Abiotic Factors

Nonliving components of environment such as temperature, pressure, and pH

Sexually

Organism must spend much more time and energy required to build an offspring

Homologous Chromosomes

Pair of chromosomes that are the same size, same appearance and same genes

When modeling foraging behavior, biologists assume that food occurs only in ___________.

Patches

Allopatry occurs when ______________.

Populations become separated geographically

Homeostasis

Process by which organisms maintain a relatively stable internal environment

Conjugation

Process in which asexual species exchange genetic information through a temporary portal

Thermoregulation

Process of maintaining an internal temperature within a tolerable range

Genetic Drift

Random change in allele frequencies that occurs in small populations

Which is the best description of the niche of a salmon?

Salinities between 0 and 3000 ppm

Plasticity is most adaptive when the environment changes __________ throughout an organism's life.

Slowly and predictably

When populations become geographically separated for a period and then come back into contact, they __________ become different species.

Sometimes

The age at maturity is the age at which an organism _____________.

Starts to reproduce

The niche of a fish is defined by ______________.

Temperature, salinity, pH, and other species of fish

What is Fitness?

The ability of an individual to survive and reproduce in its specific environment

Phenotypic Plasticity

The ability of an organism to change its phenotype in response to changes in the environment

Environmental Tolerance

The abiotic and biotic limits to survival and reproduction imposed by an organism's physiology, anatomy, and behavior

The primary cost of tanning is ______________.

The energy needed to produce melanin

True or False? Given a limited supply of energy, fish acclimated to a high temperature should outperform fish acclimated to a low temperature, when tested at high temperature.

True. If there is a limited supply of energy, then the fish acclimated to the high temp will outperform.

True or False? The observed increase in CTmax likely reflects greater swimming performance at 4°C.

True. If there is an observation of acclimation then the performance is greater.

True or False? Natural selection will likely eliminate deleterious alleles more quickly with sexual reproduction than with asexual reproduction.

True. It causes beneficial alleles to spread faster and bad alleles to be selected against.

True or False? When an organism moves from sun to shade, it reduces heating by conduction.

True. It reduces heat by radiation and conduction due to losing heat to the ground.

True or False? As the risk of death increases, an organism should reproduce earlier and more often.

True. It will increase fitness.

True or False? If a pygmy were to mate with an African of normal size, the offspring would likely be intermediate in size.

True. It would be a cross.

True or False? Two species mate but their offspring die before reaching adulthood. A more efficient way to prevent interbreeding would be to have incompatible genitals.

True. It would be a prezygotic barrier that would prevent interbreeding between two different species.

True or False? If your professor in the video were behaving optimally, he should have opened a new bag of potato chips instead of eating crumbs from an old bag.

True. It would produce the most net benefits.

True or False? Directional selection is more likely to be weak than strong.

True. More cases of weak directional selection than strong directional selection.

True or False? If a population doubles in size, a deleterious allele should become less likely to drift to a higher frequency.

True. Natural selection takes over in a larger population.

True or False? In a rapidly changing environment, a population would likely benefit more from sexual reproduction than from asexual reproduction.

True. Sex allows a population to adapt quickly and have a lot of genetic variation.

True or False? Genetic drift should affect have a bigger effect on the evolution of small populations.

True. Small populations promote genetic drift (1/2N) where N is population.

True or False? African pygmies are likely to live in risky environments, where the probability of survival is low compared to other environments where humans live.

True. That is why they must mature quicker.

True or False? The enzymes of animals in old vents should be more flexible than those of animals in young vents.

True. The old vents are much colder so the enzymes must be flexible enough to cause that reaction.

True or False? If Mendel had compared traits controlled by genes on the same chromosome, his results would not have matched the predictions of his model.

True. The results would be different from his model.

True or False? Speciation occurs more often between allopatric populations than it does between sympatric populations.

True. The separation due to geographical changes causes the speciation.

True or False? All else being equal, an organism that grows more in a given period will reproduce less during that period.

True. They will reproduce once matured.

True or False? An endotherm is more likely than an ectotherm to have a narrow thermal niche.

True. This is because endotherms have a closely regulated body temperature.

True or False? Given unlimited food, shrews should enter torpor on cold nights.

True. With unlimited food, shrews don't have to work about the cost of staying warm.

Optimization Model

Views foraging behavior as a compromise between benefits of nutrition and costs of obtaining food

The thermal niche of a desert organism ______________.

Will differ from that of a polar organism

True or False? If a parent passes one copy of each chromosome to offspring, alleles on the same chromosome would be inherited together.

True. Alleles on the same chromosome will be inherited together.

True or False? Pygmies likely evolved because individuals who reproduced early in life were more fit than individuals who reproduced later in life.

True. Fitness is increased when they reproduced earlier.

True or False? Genetic drift occurs whenever a random event causes a genotype to reproduce more than others in a population.

True. Genetic drift occurs by due to a random event.

True or False? If the parameter for the squared term is negative, natural selection will likely stabilize the phenotype at an intermediate value.

True. If the squared term is negative, then selection will likely stabilize.

Postzygotic Barriers

A barrier that prevent the hybrid zygote from becoming a fertile adult

Founder Effect

A change in allele frequencies as a result of the migration of a small subgroup of a population

Bottleneck Effect

A change in allele frequency following a dramatic reduction in the size of a population

Haploid

An organism or cell having only one complete set of chromosomes.

Binary Fission

A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size

Evolutionary Species

A group of individuals that share unique similarities of their genetics

What is a species?

A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding

Biological Species

A group of populations whose members have the potential to produce fertile offspring

Species

A group of similar organisms that can breed and produce fertile offspring

Negative Feedback

A primary mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation

Prezygotic Barriers

A reproductive barrier that impedes mating between species or hinders fertilization if interspecies mating is attempted

An organism that invests energy primarily in growth, likely lives in ___________?

A safe environment

Ecological Niche

A specific role of a species within an ecosystem including its use of resources and relationships with other species

Dynamic Equilibrium

A state of balance between continuing processes

Diploid

An organism or cell having two sets of chromosomes

True or False? If each tree contained fewer insects, the bird should spend more time feeding on a tree before searching for a new tree.

True. If there are few insects, the energy is depleted quickly and the bird should conserve.

True or False? If energy gain remained constant over time, the bird would maximize energy gain by staying on the tree forever.

True. If there is a constant supply of energy, the bird would stay.

Genomes

All the genetic material in an organism

Which type of selection is most common?

All three can happen to some extent

Hybrid

An animal carrying genes from two species

Stabilizing Selection

The mean of the trait remains similar over time but the standard deviation decreases

Directional Selection

The mean phenotype shifts in a particular direction

Meiosis

The nuclear division that forms haploid cells is called meiosis. This process of meiosis can be broken into two parts: 1) Meiosis I- a cycle through which a diploid cell divides to create two haploid cells, each receiving one of the homologous chromosomes 2) Meiosis II- a cycle through which the two haploid cells divide form four haploid cells, which later develop into sperm or eggs

Disruptive Selection

The standard deviation of the trait increases as individuals with the mean value disappear

What if animals must learn to catch food?

Then they will have to expend energy before gaining it. The rate of return will be slow at first.

Organisms such as the Antarctic fish can swim at extremely low temperatures. Which mechanism best describes how they do this?

They modify their proteins to be more flexible