B7 - Ecosystems

HideShow resource information
What is a perferct closed loop system?
When no materials enter or leave the system. Waste products from one organism or process are used by another organism or process. It can be said, therefore, that the output from one part of the system becomes the input to another part.
1 of 27
Why can no ecosystem be a perfect closed loop system?
Because some output is always lost, eg some organisms migrate, some nutrients are transported away by the wind or by rain and rivers.
2 of 27
Give an example of recycling waste products in a system
Oxygen is a waste product from photosynthesis. It is used in respiration. Carbon dioxide is a waste product from respiration. It is used in photosynthesis.
3 of 27
What happens to dead organic matter in a natural ecosystem?
Dead organic matter (eg fallen leaves, fruits, flowers, faeces, remains of bodies) is used directly as food or processed into useful nutrients by microorganisms. These microorganisms use digestive enzymes to break down complex molecules into simpler
4 of 27
GIve 1 stage of the carbon cycle (1)
Carbon exists in the atmosphere as carbon dioxide. This can be taken out of the atmosphere by the process of photosynthesis - the carbon then becoming part of glucose molecules.
5 of 27
Give the next stage of the carbon cycle (2)
These glucose molecules are then broken down during respiration. The process of respiration releases carbon back into the atmosphere as carbon dioxide.
6 of 27
GIve 2 more stages of the carbon cycle (3)
Carbon dioxide could also be released into the atmosphere by combustion of wood and fossil fuels. Microorganisms and some animals feed on dead organic matter. The carbon then becomes part of these microorganisms.
7 of 27
Why do mammals produce a very small number of eggs but millions of sperm?
Because the fertilised egg develops inside the female, so there is a greater chance of it surviving.
8 of 27
Why do fish and amphibians produce large numbers of eggs?
Because fertilisation takes place outside the body and the fertilised eggs are rarely cared for by the adults.
9 of 27
Why is vegetation an essential part of many ecosystems?
Photosynthesis - plants use the energy from sunlight to convert water and carbon dioxide into glucose and oxygen. Both glucose and oxygen are essential for animals
10 of 27
Why else is vegetation important in the environment?
Roots help to stabilise the soil – preventing it from being eroded by heavy rain (especially in rainforests). Vegetation also reduces soil erosion since foliage protects the soil from direct rainfall.
11 of 27
Give two reasons why trees are essential in most ecosystems?
Trees provide shade from the sun and help to insulate the forest floor at night – therefore stabilising the temperature. Transpiration from trees helps to promote cloud formation.
12 of 27
Why do humans rely on natural ecosystems?
They provide many ‘ecosystem services’- such as pollination of crops, and cleaning air and water. Humans also rely on ecosystems to provide them with fertile soil, mineral nutrients, fish and game.
13 of 27
Give examples of human waste that can affect ecosystems
Household waste. Industrial waste. Agricultural waste. Gases produced when fossil fuels are burned
14 of 27
How do humans unbalance ecosystems?
Human waste enters other natural ecosystems, where it can cause them to become unbalanced. Humans sometimes harvest plants and animals from natural ecosystems and this can also unbalance them.
15 of 27
Give an example of humans unbalancing ecosystems
harvesting timber can lead to soil erosion and loss of habitat, while harvesting fish from the oceans can cause species to become threatened and unbalance food webs.
16 of 27
Explain why removing natural vegetation and growing crops for biofuel is bad
As well as destroying the natural habitat and reducing biodiversity, soil erosion can cause rivers to become silted up (clogged up with silt), plus the lack of shade and the lack of moisture in the soil can cause desertification
17 of 27
How can humans removing organisms/substances from an ecosystem be sustainable?
If the rate at which we remove them is less than or equal to the rate at which they can be replaced by natural processes, such as reproduction.
18 of 27
What type of energy does crude oil have?
‘Fossil Sunlight Energy’. - Energy that was captured by photosynthesis millions of years ago when the organisms were alive and then buried underground for millions of years.
19 of 27
Why does burning 'Fossil Sunlight Energy' unbalance ecosystems?
In a perfect closed loop system, the inputs and outputs of the organisms are balanced - but the system that formed the crude oil no longer actually exists, so the input when crude oil is burned unbalances the present system (it is an ‘extra’ input).
20 of 27
What is a biofuel?
A fuel produced from renewable resources - such as plant biomass - where the carbon dioxide emitted by burning them is balanced by the carbon dioxide absorbed by the plants as they grow.
21 of 27
How can we preserve fish populations?
By observing quotas, which means that each country has an entitlement to catch only a certain number of each type of fish. Some animal populations can be restocked.
22 of 27
Give an example of tensions between conservation efforts and the needs of local communities.
even though the process of mining for gold in the Brazilian rainforest damages the natural ecosystem, the people employed as miners still need to earn money to support their families.
23 of 27
What is bioaccumulation?
Bioaccumulation is when toxins build up in a food chain. The animals at the top of the food chain are affected most severely.
24 of 27
What is the first stage of bioaccumulation?
Small amounts of toxic substances - often from human activity - are taken up by plants. These plants are eaten by primary consumers.
25 of 27
What is the second stage of bioaccumulation?
The primary consumers are eaten by secondary consumers, and the secondary consumers are eaten by higher level consumers.
26 of 27
What is the final stage of bioaccumulation?
At each stage of the food chain, harmless substances are excreted but the toxins remain in the tissues of the organisms - so the concentration of toxin becomes most concentrated in the body tissues of the animals at the top of the food chain.
27 of 27

Other cards in this set

Card 2

Front

Why can no ecosystem be a perfect closed loop system?

Back

Because some output is always lost, eg some organisms migrate, some nutrients are transported away by the wind or by rain and rivers.

Card 3

Front

Give an example of recycling waste products in a system

Back

Preview of the front of card 3

Card 4

Front

What happens to dead organic matter in a natural ecosystem?

Back

Preview of the front of card 4

Card 5

Front

GIve 1 stage of the carbon cycle (1)

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Ecology and Environmental Science resources »