Exam 3 (Ecology)

Question 1

What is Genetic Drift?

Answer 1

Genetic drift is when allele frequencies change in a population due to random events

Question 2

What is the Founder Effect

Answer 2

The loss of genetic variation that occurs when a small group of individuals establish a new population.

Question 3

What is the Bottleneck effect

Answer 3

The Bottleneck Effect happens when a population is drastically reduced by a random event (like a natural disaster), leaving behind a smaller group with different allele frequencies and less genetic diversity.

Question 4

What is Gene Flow?

Answer 4

The movement of alleles between populations when individuals migrate and reproduce, which increases genetic diversity.

Question 5

What is Natural Selection

Answer 5

Natural selection is the process where organisms with traits that help them survive and reproduce are more likely to pass on those traits to the next generation.

Question 6

What is Allele Fixation

Answer 6

When a specific version of an allele becomes the only version of that gene in a population.

Question 7

What is a population?

Answer 7

A population is a group of individuals of the same species that live in the same area and can reproduce with each other.

Question 8

What is Evolution?

Answer 8

Evolution is the change in the traits of a population over generations due to processes like natural selection, genetic drift, mutation, and gene flow.

Question 9

What is a Density Dependent Factor?

Answer 9

A factor that affects population growth more as the population size increases (disease, competition, predation).

Question 10

What is a Density Independent Factor?

Answer 10

A factor that affects population growth regardless of population size (natural disasters, weather, human activities).

Question 11

How do density-dependent factors impact population growth curves?

Answer 11

They slow growth as the population nears carrying capacity, causing the growth curve to level off (logistic growth).

Question 12

How do density-independent factors impact population growth curves?

Answer 12

They cause sudden drops in population size regardless of its current size, often creating sharp declines or fluctuations.

Question 13

Give an example of a density-dependent factor.

Answer 13

Disease spreading faster in crowded populations.

Question 14

Give an example of a density-independent factor.

Answer 14

A hurricane destroying a habitat.

Question 15

How do density-dependent factors relate to evolution?

Answer 15

They cause competition and survival challenges, leading to natural selection.

Question 16

How do density-independent factors relate to evolution?

Answer 16

They cause random population changes, leading to genetic drift.

Question 17

What is a community?

Answer 17

All the different populations of species living together in the same area.

Question 18

What is an ecosystem?

Answer 18

A community plus the non-living (abiotic) environment, like air, water, and soil.

Question 19

What is carrying capacity and how can you recognize it using a line of best fit?

Answer 19

Carrying capacity is the maximum population size that an environment can support. On a graph, it’s shown where the population size levels off and the line of best fit becomes nearly flat.

Question 20

What is reproductive lag in a predator-prey population graph, and why does it occur?

Answer 20

Reproductive lag is the delay between changes in the prey population and the predator population response. It happens because predators take time to reproduce and increase their numbers after prey become abundant.

Question 21

What are predator-prey curves?

Answer 21

They are graphs showing how predator and prey populations rise and fall in cycles, with predator numbers usually lagging behind prey numbers.

Question 22

What is resource partitioning?

Answer 22

When species divide resources or habitats to reduce competition and coexist.

Question 23

How does resource partitioning affect growth curves?

Answer 23

It allows populations to grow steadily without one outcompeting the other, leading to stable or increasing growth.

Question 24

What is competitive exclusion?

Answer 24

Competitive exclusion is when two species compete for the same resource, and one species outcompetes and excludes the other from that resource.

Question 25

How does resource partitioning relate to natural selection, adaptation, and genetic diversity?

Answer 25

Resource partitioning reduces competition, so species adapt to use different resources or habitats. Natural selection favors these adaptations, which increases genetic diversity within and between species.

Question 26

What is inbreeding and how does it affect evolution?

Answer 26

Inbreeding is mating between closely related individuals. It reduces genetic diversity and can increase harmful traits, which affects natural selection and genetic drift by making populations less adaptable.

Question 27

What are trophic levels in a food web?

Answer 27

Trophic levels show the feeding position of organisms: Producers (make energy from sunlight) Primary consumers (eat producers) Secondary consumers (eat primary consumers) Tertiary consumers (eat secondary consumers) Decomposers (break down dead matter)

Question 28

What is a keystone species?

Answer 28

A keystone species has a large impact on its ecosystem, keeping it balanced and supporting many other species, even if it isn’t the most abundant.

Question 29

How does population size change in response to changes in other populations in a food web?

Answer 29

If a prey population increases, its predators’ populations usually increase later. If a predator population grows, prey populations tend to decrease. Changes ripple through the food web affecting many species.

Question 30

How does energy move through food webs?

Answer 30

Only about 10% of the energy from one trophic level is passed to the next level; the rest is lost as heat or used by the organism.

Question 31

How do you calculate energy transfer?

Answer 31

Multiply the energy available at one level by 0.10 (10%) to find energy available to the next level.

Question 32

What are the steps in a eutrophic event and why do they occur?

Answer 32

Increase in nutrients (like nitrogen & phosphorus): Usually from fertilizer runoff or sewage. Algal bloom: Nutrients fuel rapid algae growth on the water surface. Algae die and decompose: When algae die, decomposers break them down. Oxygen used up: Decomposition uses a lot of oxygen in the water. Low oxygen (hypoxia): Fish and other aquatic life struggle or die because of lack of oxygen.

Question 33

Elephant seals compete for mates during the breeding season. As populations increase, competition for mates may intensify, leading to reduced reproductive success for some individuals. A. Density dependent B. Density independent

Answer 33

A. Density Dependent

Question 34

Monarch caterpillars will perish if they do not have enough milkweed to consume. Overconsumption of milkweed is a density _____ reduction factor and a(n) ____ factor. A. dependent ... abiotic B. independent ... biotic C. independent ... abiotic D. dependent ... biotic

Answer 34

D. Dependent...biotic

Question 35

Extra CO2 in oceans (due to climate change) hurts the ability of shell building organisms to build shells by lowering pH. a. Genetic drift event via a density independent reduction factor. b.Genetic drift event via a density dependent reduction factor. c. Natural selection event via a density independent reduction factor. d.Natural selection event via a density dependent reduction factor.

Answer 35

c. Natural selection event via a density independent reduction factor.

Question 36

Flu spreads through a poultry farm. Birds that had flu shots are less likely to get seriously sick and die. A. Genetic drift event via a density independent reduction factor. B. Genetic drift event via a density dependent reduction factor. C. Natural selection event via a density independent reduction factor. D. Natural selection event via a density dependent reduction factor.

Answer 36

D. Natural selection event via a density dependent reduction factor.

Question 37

What is Biotic?

Answer 37

Biotic refers to all the living parts of an ecosystem, like plants, animals, bacteria, and fungi.

Question 38

What does abiotic mean?

Answer 38

Abiotic refers to the non-living parts of an ecosystem, like sunlight, temperature, water, and soil.