b17 - organising an ecosystem

Question 1

how can green plants and algae photosynthesise?

Answer 1

use sunlight as a source of energy

Question 2

how are plant cells made?

Answer 2

glucose from photosynthesis is synthesised into other compounds to make plant cells
- new material adds to biomass of organism

Question 3

how do food chains begin?

Answer 3

plants are producers of biomass and start a food chain

Question 4

what animals eat producers?

Answer 4

• primary consumers
• e.g: herbivores like sheep or fish that eat phytoplankton

Question 5

what eats primary consumers?

Answer 5

secondary consumers
- animals such as seals or lions

Question 6

what are secondary consumers eaten by?

Answer 6

tertiary consumers

Question 7

how can we present feeding relationships in a community?

Answer 7

food chains

Question 8

why do primary consumers need to eat a lot of plant material?

Answer 8

• cellulose is difficult to digest so they have to eat enough to gain enough nutrients
• plants stay in one place so consumers dont expend energy chasing them

Question 9

what are secondary and tertiary consumers known as?

Answer 9

predators because they have to catch their food

Question 10

what happens to number of predators and prey in a stable community?

Answer 10

numbers rise and fall in cycles

Question 11

how is glucose made for animas to eat?

Answer 11

• carbon (abiotic) is taken in by plants and converted to glucose (biotic)
• plants take mineral ions from soil (abiotic) and these, with glucose, enter animals when plants are eaten (biotic)

Question 12

why must materials be returned to the environment?

Answer 12

for use by future organisms

Question 13

how are materials returned to environment?

Answer 13

• trees shed leaves
• animals produce droppings
• eventually all organisms die

Question 14

define decomposers and give two examples

Answer 14

• break down waste material and dead organisms
• bacteria and fungi

Question 15

what do detritus feeders do (e.g maggots, worms)?

Answer 15

start process of decay by eating waste of dead organisms

Question 16

what do decomposers do after detritus feeders?

Answer 16

digest dead animals, plants and detritus feeders, returning carbon dioxide, water and mineral ions to environment

Question 17

what is the main point of the water cycle?

Answer 17

provides fresh water for animals and plants on land before draining into the seas and oceans

Question 18

give the process of the water cycle

Answer 18

• water evaporates constantly from land surface, rivers and seas
• as water rises into cooler air, it condenses, forming clouds, and is then precipitated back into the surface as rain, snow, hail or sleet
• water passes through animals and plants then released during respiration and decay
• water also lost through urine, faeces and sweat
• plants release water into atmosphere during transpiration

Question 19

give key stages of water cycle

Answer 19

1) condensation
2) precipitation
3) evaporation
4) transpiration
5) respiration

Question 20

what does the carbon cycle involve?

Answer 20

photosynthesis and respiration

Question 21

what does photosynthesis do?

Answer 21

removes carbon dioxide from the atmosphere which is used to make organic molecules (carbs, fats and proteins)

Question 22

how is carbon dioxide returned back to atmosphere?

Answer 22

green plants and algae respire

Question 23

how is carbon dioxide released into the atmosphere?

Answer 23

when humans cut down and burn trees (combustion)

Question 24

why do animals have carbon in their bodies?

Answer 24

from eating green plants

Question 25

what happens when plants or animals die?

Answer 25

• microorganisms release the carbon i their bodies back into the atmosphere as carbon dioxide through respiration
• mineral nutrients are returned to the soil

Question 26

what does the combustion of wood and fossil fuels do?

Answer 26

releases carbon dioxide into the atmosphere

Question 27

what does a stable community do?

Answer 27

recycles all nutrients it takes up