19 Organisms and their environment and 20 Human influences on ecosystems

Question 1

food web

Answer 1

a network of
interconnected food chains and interpret food
webs

Question 2

producer

Answer 2

an organism that makes
its own organic nutrients, usually using energy
from sunlight, through photosynthesis

Question 3

consumer

Answer 3

an organism that gets its
energy by feeding on other organisms

Question 4

herbivore

Answer 4

an animal that gets its
energy by eating plants

Question 5

carnivore

Answer 5

an animal that gets its
energy by eating other animals

Question 6

decomposer

Answer 6

an organism that gets
its energy from dead or waste organic material

Question 7

trophic level

Answer 7

the position of an
organism in a food chain, food web or ecological
pyramid

Question 8

population

Answer 8

a group of organisms of
one species, living in the same area, at the same
time

Question 9

community

Answer 9

all of the populations
of different species in an ecosystem

Question 10

ecosystem

Answer 10

a unit containing the
community of organisms and their environment,
interacting together

Question 11

state the factors affecting the rate
of population growth for a population of an
organism

Answer 11

food supply, competition,
predation and disease

Question 12

how humans have increased food
production

Answer 12

(a) agricultural machinery to use larger areas of
land and improve efficiency
(b) chemical fertilisers to improve yields
(c) insecticides to improve quality and yield
(d) herbicides to reduce competition with weeds
(e) selective breeding to improve production by
crop plants and livestock

Question 13

the reasons for habitat destruction

Answer 13

(a) increased area for housing, crop plant
production and livestock production
(b) extraction of natural resources
(c) freshwater and marine pollution

Question 14

biodiversity

Answer 14

the number of different
species that live in an area

Question 15

Describe the reasons for habitat destruction

Answer 15

(a) increased area for housing, crop plant
production and livestock production
(b) extraction of natural resources
(c) freshwater and marine pollution

Question 16

effects of deforestation

Answer 16

reducing biodiversity, extinction, loss of soil,
flooding and increase of carbon dioxide in the
atmosphere

Question 17

Explain the process of eutrophication of water

Answer 17

• increased availability of nitrate and other
  ions
• increased growth of producers
• increased decomposition after death of
  producers
• increased aerobic respiration by decomposers
• reduction in dissolved oxygen
• death of organisms requiring dissolved
  oxygen in water

Question 18

sustainable resource

Answer 18

one which is
produced as rapidly as it is removed from the
environment so that it does not run out

Question 19

Describe how endangered species can be
conserved

Answer 19

(a) monitoring and protecting species and
habitats
(b) education
(c) captive breeding programmes
(d) seed banks

Question 20

Describe the reasons for conservation
programmes

Answer 20

(a) maintaining or increasing biodiversity
(b) reducing extinction
(c) protecting vulnerable ecosystems
(d) maintaining ecosystem functions, limited
to nutrient cycling and resource provision,
including food, drugs, fuel and genes

Question 21

Explain how forests can be conserved

Answer 21

education, protected areas, quotas and replanting

Question 22

Explain how fish stocks can be conserved

Answer 22

education, closed seasons, protected areas,
controlled net types and mesh size, quotas and
monitoring

Question 23

Describe the use of artificial insemination (AI)
and in vitro fertilisation (IVF) in captive breeding
programmes