Unit 7.1 - stability and change

Question 1

Ecosystems

Answer 1

Biological communities of interacting organisms and their physical environment

Question 2

Tipping points

Answer 2

A critical threshold that, when crossed, leads to large and often irreversible changes in the climate system

Question 3

Mesocosm

Answer 3

Any indoor experimental system that examines the natural environment under controlled conditions

Question 4

Keystone species

Answer 4

Species that have a disproportionate effect on the structure of their community

Question 5

Sustainable fishing

Answer 5

Harvesting fish at a sustainable rate; where the fish population does not decline over time because of fishing

Question 6

Sustainable harvesting

Answer 6

Where the rate of harvesting is lower than the rate of replacement or the removal of the parts of a plant without damaging the health of the plant

Question 7

Maximum sustainable yield

Answer 7

Is the largest catch of fish that can be sustained over time without causing the fish stocks to decrease

Question 8

Eutrophication

Answer 8

A process in which aquatic ecosystems become overly enriched with nutrients, leading to plentiful algal growth

Question 9

Biological oxygen demand (BOD)

Answer 9

The amount of dissolved oxygen that microorganisms need to break down organic materials in water

Question 10

Biomagnification

Answer 10

Is the increase in concentration of a substance, such as a pesticide, in the tissues of organisms at successively higher levels in a food chain

Question 11

DDT

Answer 11

Is a pesticide which can be biomagnified in food chains. It was used to kill insects and pests, but DDT was also found in their tissues. It is stored in fat tissues and does not readily breakdown. Insects are eaten by fish which are eaten by ospreys and so high concentrations of DDT are accumulated in the tissues of ospreys by biomagnification.

Question 12

Minimata disease

Answer 12

Is a neurological disease caused by the biomagnification of methylmercury in an ecosystem

Question 13

Plastics

Answer 13

A range of organic synthetic materials that persist in the environment because they do not biodegrade

Question 14

Microplastics

Answer 14

Produced by the physical breakdown of macroplastics (less than 1mm across)

Question 15

Biodegradable

Answer 15

Capable of being broken down by natural, biological processes

Question 16

Apex predator

Answer 16

Predators at the top of the food-chain

Question 17

Rewilding

Answer 17

Aims to restore degraded ecosystems back to their natural state by reintroducing keystone species, creating wildlife corridors and/or reducing human impact

Question 18

Wildlife corridors

Answer 18

Are areas of habitat which connect wildlife populations separated by human activities or structures e.g roads