Population Growth and Interactions - Chapter 20 - Unit 6

Question 1

Define population density

a) in a words
b) in form of an equation

Answer 1

a) Ecologist use various sampling methods to estimate the density of a population
b) Dp = N/A or Dp = N/V

Question 2

List two factors that influence the distribution patterns of populations

Answer 2

The main factors determining population distribution are :

climate, landforms, topography, soil, energy and mineral resources,

Question 3

Uses examples ( one for each population distribution pattern to explain how random distribution is different from clumped distribution and uniform distribution

Answer 3

Individuals may be distributed in a uniform, random, or clumped pattern. Uniform means that the population is evenly spaced, random indicates random spacing, and clumped means that the population is distributed in clusters.

Example: The golden eagle is a species that exhibits uniform distribution

Question 4

Names the four basic process that cause changes in pollution size, and write the question summarizes their relationship

Answer 4

a) natality
b) mortality
c) immigration
d) emigration

gr = N/t

Question 5

Explain the difference between the growth rate of a pollution and the per capita growth rate of a population

Answer 5

First, population size is influenced by the per capita population growth rate, which is the rate at which the population size changes per individual in the population. This growth rate is determined by the birth, death, emigration, and migration rates in the population.

Question 6

Define biotic potential, and give its symbol.

Answer 6

Symbol r.

The number of offspring of an individual organism that would survive to reproductive age under ideal conditons. It is a measure of an individual’s reproductive potential, although this is seldom fully realized under natural conditons.

Question 7

Name four factors that determine the biotic potential of a species

Answer 7

• The number of offspring that survive per reproductive cycle
• The number of offspring that survive long enough to reproduce
• The age of reproductive maturity and the number of times that the individuals reproduce in a life span
• The life span of the individuals

Question 8

What is an exponential growth pattern? What is its shape in a graph?

Answer 8

• Exponential growth is a pattern of data that shows sharper increases over time.
• Exponential growth produces a J-shaped curve, while logistic growth produces an S-shaped curve.

Question 9

Explain how biotic potential and exponential growth are related.

Answer 9

When resources are unlimited and a society reads its biotic potential, this results in a society with high fertility and exponential growth. If you put this into a graph, the population increases exponentially over time.

Question 10

Define carrying capacity, and give its symbol

Answer 10

The carrying capacity (symbol: K)

For a biological species is marked by the red dotted horizontal line to describe the number of organisms that the environment can support sustainably for a given time.

Question 11

Explain, using at least two example, the differences between density-dependent factors and density- independent factors.

Answer 11

Density dependent factors are those that regulate the growth of a population depending on its density while density independent factors are those that regulate population growth without depending on its density.

Example : Parasites and Disease; kill or most of the mosquitoes

Question 12

What is the environmental resistance? How does it affect populations

Answer 12

Environmental resistance factors are things that limit the growth of a population. They include biotic factors - like predators, disease, competition, and lack of food - as well as abiotic factors - like fire, flood, and drought. The biotic potential of a population is how well a species is able to survive.

Question 13

Distinguish between intraspecific competition and interspecific competition.

Answer 13

• Interspecific competition occurs between individuals of different species.
• Intraspecific competition occurs between individuals of the same species.

Question 14

Explain how intraspecific competition limits the great rate of a population

Answer 14

However, as the population reaches its maximum (the carrying capacity), intraspecific competition becomes fiercer and the per capita growth rate slows until the population reaches a stable size.

Question 15

State what can happen when a non-native (introduced) species competes with native species

Answer 15

Invasive species compete with native species for resources like space, light, water, and food. They can also directly prey on native species (in the case of invasive species like wild pigs or Asian giant hornets) or carry diseases and parasites that can spread to native species.

Question 16

How do producer - consumer relationships put selective pressure on both partners?

Answer 16

A selective pressure is any reason for organisms with certain phenotypes to have either a survival benefit or disadvantage

Question 17

Explain the difference between Batesian and Mullerian mimicry

Answer 17

Batesian mimicry is the exhibition of the characteristics of a dangerous species by a harmless species to avoid predators whereas Mullerian mimicry is the exhibition of similar characteristics by similar species to avoid predator

Question 18

Define Symbiosis

Answer 18

interaction between two different organisms living in close physical association, typically to the advantage of both.

Question 19

Give one example of mutualism, and explain how the partners in relationship benefit.

Answer 19

Oxpeckers land on rhinos or zebras and eat ticks and other parasites that live on their skin. The oxpeckers get food and the beasts get pest control. Also, when there is danger, the oxpeckers fly upward and scream a warning, which helps the symbiont

Question 20

Define Commensalism

Answer 20

An association between two organisms in which one benefits and the other derives neither benefit nor harm.

Question 21

Explain how parasitism is different from mutualism and commensalism

Answer 21

• Mutualism is where both organisms benefit,
• Commensalism is where one benefits and the other is unaffected, and
• parasitism is where one benefits and the other is harmed

Question 22

What is succession

Answer 22

Succession is the change in either species composition, structure, or architecture of vegetation through time.

Question 23

Distinguish between

a) primary succession and secondary succession
b) pioneer community and climax community

Answer 23

a) primary succession and secondary succession

In primary succession, newly exposed or newly formed rock is colonized by living things for the first time.

In secondary succession, an area previously occupied by living things is disturbed—disrupted—then recolonized following the disturbance.

b) Pioneer community and Climax Community

Climax community: It is a type of community that has reached the stable stage, in an extensive and well defined term known as biome.

Pioneer community: It is a first biotic community which grows on uncovered land.

Question 24

Define Sustainability

Answer 24

the ability to be maintained at a certain rate or level.

Question 25

What is an age pyramid?

Answer 25

A population pyramid is a graph that shows the distribution of ages across a population divided down the center between male and female members of the population. The graphic starts from youngest at the bottom to oldest at the top.