Niche and Parasite Life Cycles

Question 1

What is an ecological niche?

Answer 1

A multi dimensional summary of the tolerances and requirements of a species.

Question 2

What is a fundamental niche?

Answer 2

The niche a species occupies in the absence of any interspecific competition.

Question 3

What is a realised niche?

Answer 3

The niche a species occupies when there is interspecific competition.

Question 4

What can be the result of interspecific competition?

Answer 4

Competitive exclusion.

Question 5

What is competitive exclusion?

Answer 5

Where the niches of two species are so similar that one species declines to extinction.

Question 6

How can potential competitors live simultaneously when their niches are sufficiently different?

Answer 6

By resource partitioning.

Question 7

What is parasitism?

Answer 7

A symbiotic relationship between parasite and host.

Question 8

Who benefits in a parasitic symbiotic relationship?

Answer 8

The parasite - it gains nutrients.

Question 9

How has greater reproductive ability - parasite or host?

Answer 9

Parasite.

Question 10

Why do most parasites have a narrow niche?

Answer 10

As they are very host specific.

Question 11

Why are many parasites degenerate?

Answer 11

As the host provides so many of the parasites needs.

Question 12

Where do ectoparasites live?

Answer 12

On the surface of its host.

Question 13

Where do endoparasites live?

Answer 13

Within the tissue of the host.

Question 14

What is a definitive host?

Answer 14

The organism in which the parasite reaches sexual maturity.

Question 15

What is the role of a vector?

Answer 15

Transmission of the parasite and sometimes act as hosts.

Question 16

What causes malaria?

Answer 16

Plasmodium.

Question 17

How is malaria spread?

Answer 17

An infected mosquito, acting as a vector, bites a human.
Plasmodium enters blood stream.
Asexual reproduction occurs in liver and red blood cells.
Red blood cells burst and gametocytes released into bloodstream.
Mosquito bites infected human - gametocytes enter mosquito and sexual reproduction occurs.
Mosquito infects another human.

Question 18

What do Schistosomes cause?

Answer 18

Schistosomiasis.

Question 19

How do schistosomes cause infection?

Answer 19

They reproduce sexually in human intestine.
Fertilised eggs pass out via faeces into water where they develop into larvae.
Larvae infect water snails and asexually reproduce.
This produces another type of motile larvae which escape the snail and penetrate the skin of human.

Question 20

What are viruses?

Answer 20

Parasites that can only replicate within a host cell.

Question 21

How is a virus’ genetic material stored?

Answer 21

As DNA or RNA and packaged in a protective protein coat.

Question 22

Some viruses are surrounded by a phospholipid membrane - where is this derived from?

Answer 22

From host cell material.

Question 23

What is found on the surface of viruses?

Answer 23

Antigens.

Question 24

Is the host cell always able to detect viruses as foreign?

Answer 24

No

Question 25

What are the stages of the viral life cycles?

Answer 25

• The virus infects the host with its genetic material
• The host cell enzymes replicate the viral genome
• Transcription and translation of viral genes and proteins
• New viral particles are produced and released