population ecology

Question 1

population

Answer 1

• A group of animals of the same species living together in an
  area

Question 2

community

Answer 2

• A group of animals of the different species living together
  in an area

Question 3

ecosystem

Answer 3

A community of living organisms interacting with one
another and with the non-living components

Question 4

immigration

Answer 4

• The movement of animals into a new area

Question 5

emigration

Answer 5

The movement of animals out of an area

Question 6

Mortality

Answer 6

The death rate or number of animals dying within a population

Question 7

Natality

Answer 7

The birth rate or number of animals born in a population

Question 8

. What is the effect of immigration, emigration, mortality and natality on
population size?

Answer 8

Natality and immigration INCREASES the population size
Mortality and emigration DECREASES the population size

Question 9

• What are density dependent factors and briefly explain the effects of
  these on population growth?

Answer 9

Factors that limit population growth based on the size of the population(resources available) (like
competition for food, water, oxygen, space/territory, shelter as well as number
of predators, parasites and occurrence of disease)
The larger the population, the more competition, more parasites, more disease
which all limit further population growth.

Question 10

What are density independent factors and briefly explain the effects of
these on population growth.

Answer 10

Factors that affect population growth regardless of the size of the population
(natural disasters like floods, fires, earthquakes etc)
No matter how big or small a population, density independent factors will make
the population smaller.

Question 11

What is the implication of environmental resistance and carrying capacity
for a species?

Answer 11

The population’s ability to successfully access resources.
- If resources are plentiful and population is small, the population grows
exponentially.
- As numbers increase, pressure on resources occurs – environmental
resistance occurs because the environment has reached its carrying
capacity.

Question 12

What is the method of the mark- recapture method?

Answer 12

In a well-defined area:
Capture as many organisms as
possible, mark & release them.
Allow time for marked individuals to
mix with the rest of the population.
Recapture as many as possible.
Count the number of marked
individuals. Use a formula to
calculate the estimated population
size

Question 13

precautions for the mark recapture method?

Answer 13

Allow little time between 1
st & 2nd
capture to limit births & deaths.
Repeat sampling several times &
calculate averages. Marking should
not affect individuals’ movement or
behaviour. No immigration and
emigration should occur

Question 14

Method of the quadrat method?

Answer 14

Measure the size of the total
area. Randomly mark out
“frames” or quadrats of
known size within the total
area. Count the number of
individuals within each frame.
Use a formula to calculate
the estimated population size

Question 15

precautions for the Quadrat method

Answer 15

Size and area of quadrats
must be known. Quadrats
must be randomly selected.
The exact number of
organisms in each quadrat
must be counted

Question 16

Method of a census

Answer 16

Counting every
single individual in
a population

Question 17

limitations for census

Answer 17

It is only suitable for
counting stationary
or sessile
organisms (like
plants or barnacles
on rocks), slow
moving animals
(like snails) or large
animals (like
elephants

Question 18

Define predator prey relationship

Answer 18

The interaction that exists between animals that hunts for its food (predator)
and the animal that is being hunted (prey) through which the population size
of both the predators and the prey regulate the population size of the other.

Question 19

What is the impact of food webs on populations?

Answer 19

prevents prey overpopulation by regulatingq population size

Question 20

What is intra-specific competition

Answer 20

when organisms of the same species compete for the same resources at the same time

Question 21

inter-specfic

Answer 21

when organisms of different species compete for the same resource at the same time

Question 22

Explain one resource partioniong strategy among plants seen in a forest ecosystem

Answer 22

Spatial resource partioning occurs in a forest where plants grows to different heights in order to use different parts of the same resource which is light

Question 23

What are resource partioning among animals

Answer 23

Temporal- same resource at different times (dirnal and nocturnal)
Spatial- same plant but different parts

Question 24

What is meant by ecological succession

Answer 24

the process of change in different types of organisms present in an ecological community over time

Question 25

explain primary succession

Answer 25

1 .Bare rock (no soil)
2.Lichens break the rock to create soil
3.Lichens die and decompose adding nutrients to the new soil
4. mosses and simple plants grow in new soil
5.Ferns and grasses start to grow
(1-5, Pioneer)
5. Small hardy , woody plant
6. Larger shrubs and bushes
(6-8, intermediate stages)
9. Large trees (climax stages)

Question 26

explain secondary succession

Answer 26

1- soil remains
2- herbs and weeds
3-grasses
(1-3, pioneer stages)
4- small hardy, woody plants
5-larger shrubs and bushes
6- small tress
(4-6, intermediate stages)
7- Large trees ( climax stage)

Question 27

What are social organizations to enhances survival

Answer 27

• benefits of herds or flocks as a predator avoidance
  strategy as in zebra
• packs as a successful hunting strategy as in wild dogs
• animals with a dominant breeding pair as in wild dogs
• division of tasks among castes as in termites

Question 28

Explain exponential growth in a population

Answer 28

initially the population is small and can increase in size easily because there is enough resources available
however, when the populations gets too big to survive in this environment, it most likely die out

Question 29

What environmental resistance

Answer 29

enviromental factors restrict or limit the numerical increase of a population size, happens when a populations size exceeds its carrying capacity

Question 30

Explain logistic growth

Answer 30

initially population can increase in size enough resources available
however the population will get too big to survive
but unlike exponential growth, the populations doesn’t die out bur reaches equilibrium a state where natality and mortality rates are almost equal so population size remains reasonably stables

Question 31

What are the reasons for exponential human growth

Answer 31

• improved treating of diseases
  -development of vaccines
• increase in food production because of more land and fertilizer increase yield
• increase agricultural productivity because of use of more effective farming methods

Question 32

what is the importance of random sampling

Answer 32

Random sampling ensures that results obtained from your sample should approximate what would have been obtained if the entire population had been measured