Chapter 23 - Ecosystems

Question 1

Define eco-system

Answer 1

All the interacting living organisms and the non-living conditions in a defined area

Question 2

Suggest the types of factors affecting a rainforest

Answer 2

• Biotic factors (presence of trees and the size of their population, competition between two animal populations)
• Abiotic (non-living) rainfall, yearly temperatures

Question 3

What are biotic factors?

Answer 3

Interactions between organisms that are living, or have once lived

Often involve competition either within a population or between different populations (food, territory and breeding partners)

Question 4

Give examples of how some plants are adapted with different light intensities

Answer 4

-Low light= larger leaves, develop photosynthetic pigments that require less light

Question 5

What does temperature most effect in plants?

Answer 5

The enzymes

Question 6

Give 5 examples of abiotic factors

Answer 6

Light
Temperature
Water availability
Oxygen availability
Edaphic (soil) factors

Question 7

What are the ideal conditions for oxygen availability in aquatic environments

Answer 7

-Fast flowing cold water bc has high conc of oxygen

If water becomes too warm or flow rate too slow the drop in oxygen conc leads to suffocation

Question 8

What is waterlogged soil/

Answer 8

When the air spaces in between the soil particles are filled with water reducing oxygen available for plants

Question 9

What are the 3 types of soil?

Answer 9

Clay- fine particles, easily waterlogged and forms clumps when wet

Loam- Different sized particles, retains water but doesnt become waterlogged

Sandy- Well separated particles that allow free draining, easily eroded and doesn’t retain water

Question 10

What is each stage in the chain known as?

Answer 10

Trophic level

Question 11

What is the first trophic level?

Answer 11

Producer- organism that converts lights energy into chemical energy by photosynthesis

Question 12

What is the level after producer called?

Answer 12

Consumers- organisms that obtain their energy by feeding on other organisms

Primary consumer eats the producer

Question 13

Why are there rarely more than a quaternary consumer?

Answer 13

Because there is not enough biomass and stored energy left to support any further organisms

Question 14

Define biomass

Answer 14

The mass of living material present in a particular place or in particular organisms

Question 15

How do you calculate the biomass at each trophic level?

Answer 15

Biomass present in each organism x n. of organisms in that trophic level

Question 16

What is the disadvantage of biomass pyramid?

Answer 16

Represents biomass at a particular moment in time (doesn’t take into account seasonal changes)

Question 17

What would be the easiest way to measure biomass but what makes it unreliable?

Answer 17

• Measure the mass of fresh material present
• Water content must be discounted and presence of water in different organisms makes it unreliable unless large samples used

Question 18

Describe the method used by scientists to measure biomass and its disadvantage

Answer 18

• Calculate the dry mass of organisms present
• Have to be killed-> placed in oven at 80 deg. so water evaporates
• Small samples are taken to not destroy the biodiversity but this may not be representative of the whole population

Question 19

What are the units for biomass?

Answer 19

Grams per square meter (gm-2) for areas of land

Water= grams per cubic metre (gm-3)

Question 20

What is the units for energy available at each trophic level

Answer 20

kilojoules per metre squared per year (kJ m-2 yr-1)