B9 - Ecosystems and Material Cycles Flashcards
(61 cards)
1
Q
Define
Individual.
A
a single organism
2
Q
Define
Population.
A
all the organisms of one species in a habitat
3
Q
Define
Habitat.
A
the place were an organism lives
4
Q
Define
Species.
A
a group of similar organisms that can reproduce to give fertile offspring
5
Q
Define
Community.
A
all the organisms of different species living in a habitat
6
Q
Define
Ecosystem.
A
a community of organisms along with all the non-living (abiotic) conditions
7
Q
What is
Interdependence?
A
organisms depending on eachother for things like food and shelter in order to survive and reproduce
8
Q
What does interdependence mean for communities?
A
a change in the population of one species can have huge knock on effects for other species in the same community
9
Q
Define
Mutualism.
A
a relationship between two organisms from which both organisms benefit
10
Q
Define
Parasite.
A
An organisms that lives very closely with a host species. The parasite takes what it needs to survive, but the host doesn’t benefit.
11
Q
What are some
abiotic factors that affect communities?
(non-living)
(4 factors)
A
- temperature
- amount of water
- light intensity
- levels of pollutants
12
Q
What are some
biotic factors that affect communities?
(living)
(2 factors)
A
- competition
- predation
13
Q
How do you
compare how common an organism is in two sample areas?
(6 steps)
A
- Place a quadrat on the ground at a random point within the first sample area.
- Count all the organisms you’re interested in within the quadrat.
- Repeat steps 1 and 2 lots of times.
- Work out the mean number of organisms per quadrat within the first sample area.
- Repeat steps 1 to 4 in the second sample area.
- Compare the two means.
14
Q
Define
gradient.
(biology)
A
abiotic factors changing across a habitat
15
Q
How do you
use a belt transect to study distribution along a gradient?
(practical)
(5 steps)
A
- Mark out a line in the area you want to study.
- Collect data along the line using quadrats placed next to eachother.
- You could also record other data, such as the mean height of the plants you’re counting or the abiotic factors in each quadrat.
- Repeat steps 1 and 2 several times, then find the mean number of organisms or mean percentage cover for each quadrat.
- Plot graphs to see if the changing abiotic factor is correlated with a change in the distribution of the species you’re studying.
If your transect is quite long, you could place the quadrats at regular intervals instead.
Collect data by counting all the organisms of the species you’re interested in, or by estimating percentage cover.
16
Q
What is the formula for
the efficiency of energy transfer between levels of a food chain?
A
efficiency = (energy transferred to next level x 100) / energy available at previous level
17
Q
Define
Biodiversity.
A
the variety of living organisms in an ecosystem
18
Q
What are the steps for
eutrophication?
(5 steps)
A
- Fertilisers enter the water, adding excess nitrates (more than plants in the water can take in).
- The excess nitrates cause algae to grow fast and block out the light.
- Plants can’t photosynthesise due to lack of light and start to die and decompose.
- With more food available, microorganisms that feed on decomposing plants increase in number and use up oxygen in the water.
- Organisms that need oxygen for aerobic respiration (e.g. fish) die.
Pollution by sewage can also cause this eutrophication
19
Q
How can
fish farms in areas of open water reduce biodiversity in the surrounding area?
(4 steps)
A
- Food is added to the nets to feed the fish, which produce huge amounts of waste. Both the food and the waste can leak into the open water, causing eutrophication and the death of wild species.
- Fish farms in open water often act as a breeding ground for large numbers of parasites. These parasites can get out of the farm and infect wild animals, sometimes killing them.
- Predators are attracted to the nets and can become trapped in them and die.
- Sometimes farmed fish can escape into the wild, which can cause problems for wild populations of indigenous species.
20
Q
Define
Non-indigenous species.
A
A species that doesn’t naturally occur in an area.
21
Q
How can
the introduction of a non-indigenous species reduce biodiversity?
(2 ways)
A
- Non-indigenous species compete with indigenous species for resources like food and shelter. Sometimes, they are better at getting these resources and out-compete the indigenous species, which decrease in number and eventually die out.
- Non-indigenous species sometimes also bring new diseases to a habitat. These often infect and kill lots of indigenous species, reducing the habitat’s biodiversity.
22
Q
Define
Reforestation.
A
when land where a forest previously stood is replanted to form a new forest
23
Q
What are some
benefits to maintaining biodiversity?
(6 benefits)
A
- protecting the human food supply
- ensuring minimal damage to food chains
- providing future medicines
- cultural aspects
- ecotourism
- providing new jobs
24
Q
Define
Food security.
A
Having access to enough food that is safe for us to eat and has the right balance of nutrition
25
# Define
Yield.
the amount of useful product made
26
# Define
Sustainability.
meeting the needs of **today's** population **without** affecting the ability of **future** generations to meet their needs.
27
# What are the 7 most important points about the
carbon cycle?
1. There's only **one arrow** going **down** from carbon dioxide in the **air**. The whole thing is 'powered' by **photosynthesis**. **Plants** use the carbon in carbon dioxide to make **carbohydrates**, **fats** and proteins.
2. **Eating** passes the carbon compounds in the plant along to **animals** in a food chain.
3. Both plant and animal **respiration** while the organisms are alive **release carbon dioxide** back into the **air**.
4. Plants and animals eventually **die** and **decompose**, or are killed and turned into **useful products**.
5. When plants and animals decompose they're broken down by microorganisms, such as bacteria and fungi. These decomposers **release carbon dioxide** back into the air by **respiration**, as they break down the material.
6. Some useful plant and animal **products** are **burned** (**combustion**). This also releases **carbon dioxide** back into the air.
7. **Decomposition** of materials means that **habitats** can be **maintained** for the organisms that live there.
28
# What are the 4 steps to the
water cycle?
1. **Energy** from the **Sun** makes water **evaporate** from the land and sea, turning it into **water vapour**. Water also evaporates from plants by **transpiration**.
2. The warm water vapour is **carried upwards** (as warm air rises). When it gets higher up it **cools** and **condenses** to form **clouds**.
3. Water falls from the clouds as **precipitation** onto **land**, where it provides **fresh water** for **plants** and **animals**.
4. It then **drains** into the **sea** and the whole process starts again.
29
# Define
Desalination.
removing **salts** (**mineral ions**) from salt water
30
# Describe the process of
thermal desalination.
| (3 steps)
1. Salt water is **boiled** in a large enclosed vessel, so that the water **evaporates**.
2. The steam **rises** to the top of the vessel, but the salts stay at the **bottom**.
3. The steam then travels down a pipe from the top of the vessel and **condenses** back into **pure water**.
31
# Define
Osmosis.
The net movement of **water** across a **partially permeable membrane**, from an area of **higher water potential** to an area of **lower water potential**.
32
# What are the steps of
reverse osmosis?
| (3 steps)
1. Salt water is **treated** to remove solids, before being fed at a very **high pressure** into a vessel containing a **partially permeable membrane**.
2. The pressure causes the water molecules to move in the **opposite direction** to **osmosis**.
3. As the water is forced through the membrane, the **salts** are **left behind**, **removing** them from the water.
33
# Define
Nitrogen fixation.
the process of turning **N2 from the air** into **nitrogen-containg ions** in the soil which **plants can use**
34
# What are the two main ways of
nitrogen fixation?
- lightning
- nitrogen-fixing bacteria
35
Why is **nitrogen fixation** necessary?
**Nitrogen** is **needed** for making **proteins** for growth, so living organisms have to get it somehow. However, **nitrogen gas**, N2, is **very unreactive** so can't be used **directly** by plants or animals.
36
What do **decomposers** do in the nitrogen cycle?
decompose **proteins** and **urea** and turn them into **ammonia**
## Footnote
ammonia forms **ammonium ions** in solution that plants can use
37
What do **nitrifying bacteria** do in the nitrogen cycle?
turn **ammonia** in decaying matter into **nitrites** and then into **nitrates**
## Footnote
different species of nitrifying bacteria are responsible for producing nitrites and nitrates
38
What do **nitrogen-fixing bacteria** do in the nitrogen cycle?
turn **atmospheric N2** (from air pockets in the soil) into **ammnoia**, which forms **ammonium ions**
39
What do **denitrifying bacteria** do in the nitrogen cycle?
turn **nitrates** back into **N2 gas**
## Footnote
this is of no benefit to living organisms, denitrifying bacteria are often found in **waterlogged soils**
40
# What are some ways for **farmers** to
**increase** the **amount** of **nitrates** in the **soil**?
| (2 ways)
- crop rotation
- fertilisers
41
# What is
crop rotation?
**different crops** being grown each year in a field in a **cycle**
## Footnote
the cycle usually includes a **nitrogen-fixing** crop, which helps put nitrates back into the soil for another crop to use the following year
42
# Define
Indicator species.
**organisms** that are very **sensitive to changes** in their environment
43
Why are **indicator species** helpful?
they can be studied to see the effect of human activities
44
What would the presence of **stonefly larvae** signify?
| (indicator species)
the water is clean
45
What would the presence of **freshwater shrimps** signify?
| (indicator species)
the water is clean
46
What would the presence of **blood worms** signify?
| (indicator species)
the water has a very high level of water pollution
47
What would the presence of **sludgeworms** signify?
| (indicator species)
the water has a very high level of water pollution
48
What would the presence of **bushy lichen** or **lots of lichen** signify?
| (indicator species)
the air is clean
| (the concentration of sulfur dioxide in the atmosphere is low)
49
What would the presence of **crusty lichen** signify?
| (indicator species)
less clean air
| (compared to bushy lichen)
50
What would the presence of **blackspot fungus** on **rose leaves** signify?
| (indicator species)
the air is clean
| (the concentration of sulfur dioxide in the air is low)
51
What is a **more accurate** way to measure the **concentration of dissolved oxygen in the water** (**level of water pollution**)?
| (2 methods)
dissolved oxygen meter
chemical test
52
What is a **more accurate** way to measure the **concentration of sulfur dioxide in the air** (**level of air pollution**)?
| (2 methods)
electronic meter
laboratory test
53
What 3 main things does the **rate of decay** depend on?
- temperature
- water content
- oxygen availability
54
How does **temperature** affect **rate of decay**?
A **warm** temperature **speeds up** the rate of **enzyme-controlled reactions** in microbes, so decay happens **faster**. Enzymes **denature** if the temperature gets too high.
55
How does **water content** affect **rate of decay**?
decay takes place **faster** in **moist environments** because the organisms involved in decay need **water** to **survive** and carry out **biological processes**
56
How does **oxygen availability** affect **rate of decay**?
the rate of decomposition is **faster** where there is **plenty of oxygen** available
57
# What are some methods of
**food preservation** to **reduce** the rate of decay?
| (3 methods)
- storing foods in a fridge or freezer
- storing food in airtight cans
- drying food
58
How does storing foods in a **fridge** or **freezer** help **food preservation**?
it lowers the temperature of the food, this slows down the decomposers' **rate of reproduction**
| (or **stops** it altogether in the case if freezing)
59
How does storing food in **airtight cans** help **food preservation**?
This stops the microorganisms **getting in**. Once the food is in, the cans are **sealed** and **sterilised** to **kill** any microorganisms present.
60
How does **drying** food help **food preservation**?
it **removes** the **water** that microorganisms need to **survive** and **reproduce**
## Footnote
(as does adding **salt** or **sugar**, which causes the microorganisms to **lose water** by **osmosis**)
61
# Define
compost.
**decomposed organic matter** that is used as a **fertiliser** for crops and garden plants
