Topic 9 - Ecosystems and Material Cycles

Question 1

Individual

Answer 1

A single organism

Question 2

Population

Answer 2

All the organisms of one species in a habitat

Question 3

Community

Answer 3

All the organisms of different species living in a habitat

Question 4

Ecosystem

Answer 4

A community of organisms along with all the abiotic conditions

Question 5

Abiotic factors

Answer 5

Non-living factors that affect communities. Temperature, amount of water, light intensity, levels of pollutants

Question 6

Biotic factors

Answer 6

Living factors that affect communities. Competition, predation.

Question 7

How does temperature affect communities

Answer 7

Affects which species can survive in an environment

Question 8

Amount of water effect

Answer 8

Plants grow best with a certain amount of water, and animals need water to survive

Question 9

Light intensity effect

Answer 9

Certain plants survive in different light intensities, which can be changed by things such as clouds and trees

Question 10

Pollutant effect

Answer 10

Some organisms cant survive if certain pollutants are too high.

Question 11

Interdependence

Answer 11

Where organisms in a community depend on eachother for things like food and shelter to survive and reproduce.

Question 12

Mutualism

Answer 12

Relationship between two organisms that benefits both organisms. E.g plants and bees.

Question 13

Parasitism

Answer 13

A relationship between 2 organism where only one benefits and the other gets nothing in return. E.g Fleas and dogs

Question 14

Quadrat practical

Answer 14

Use a 1m quadrat to measure number of organisms inside it. Repeat lots of times and find the mean.

Question 15

Belt Transect Practical

Answer 15

Mark out a line from that spreads along a gradient of a variable(eg. shade). Collect data along the line using quadrats. Plot a graph using the info to see the change.

Question 16

How does energy get lost in food chains

Answer 16

It gets lost from thermal energy to the surroundings and not all of the organism being eaten

Question 17

What does energy loss in food chains lead to

Answer 17

Most of the energy that is passed along the food chain is lost to less useful forms. This limits the amount of trophic levels and how many organisms there are at each trophic level.

Question 18

What is a pyramid of biomass

Answer 18

Shows how much the creatures at each level of a food chain would weigh if they were all put together. It shows how much energy there is at each stage of the food chain.

Question 19

What is the formula for efficiency of energy transfer betwen levels

Answer 19

Energy transferred to next level/energy available at previous level x100

Question 20

What are three ways humans have a negative impact on biodiversity

Answer 20

Eutrophication, fish farming, introduction of non-indigenous species

Question 21

Eutrophication impact

Answer 21

Nitrates are used as fertilisers on fields. If it rains , the nitrates can fins their way into rivers and lakes. This leads to fast algae growth due to excess nitrates. The algae blocks out light so plants cant photosynthesise and die. Microorganisms that feed on dead plants increase in number and use up oxygen in the water. Organisms such as fish that need oxygen die.

Question 22

Fish farming impact

Answer 22

1. Food is added to the nets to feed the fish, which produces large amounts of waste. Both the food and waste leak into the open water, causing eutrophication and the death of wild species. 2. Leads to a breeding ground for parasites which infect wild animals. 3. Predators get attracted to the nets and can get trapped and die. 4. Fish can escape into the wild and cause problems for wild populations.

Question 23

Introduction of non indigenous species impact

Answer 23

Introduced intentionally or not. They compete with indigenous species for resources. sometimes they out-compete indigenous species which leads to them dying out. They can also bring new dieseases which kill native species.

Question 24

2 Ways humans have a positive impact on biodiversity

Answer 24

Reforestation, conservation schemes

Question 25

Reforestation impact

Answer 25

Planting new forests that have been deforested. Forest have high biodiversity because they have a wide variety of trees and plants which provide shelter for animal species.

Question 26

Conservation schemes impact

Answer 26

Used to protect at-risk species. Protect biodiversity by preventing species dying out. Methods include: 1. Protecting a species natural habitat 2. Protecting species in safe areas outside of their natural habitat and introducing breeding programmes 3. The use of seed banks to store and distribute seeds of rare and endangered plants

Question 27

Benefits of maintaining biodiversity

Answer 27

1. Protecting the human food supply
2. Ensuring minimal damage to food chains
3. Providing future medicines - plants may be abel to be used as medicines in future
4. Cultural aspects
5. Ecotourism
6. Providing new jobs

Question 28

Biological factors affecting the level of food security

Answer 28

Increasing human population, increased animal farming and meat and fish consumption, environmental changes caused by humans, sustainibility issues, new pests and pathogens.

Question 29

Describe The carbon cycle

Answer 29

Co2 in the air is used by plants for photosynthesis. Eating the plants passes on the carbon compounds to a food chain. Respiration releases co2 back into the air. Plants and animals die and decompose or are used to make useful products. When plants and animals decompose they are broken down by microorganisms such as bacteria and fungi. These decomposers release co2 back into the air by respiration. Some useful plants and animal prducts are burned whcih releases co2 to the air.

Question 30

Describe The water cycle

Answer 30

Energy from the sun makes water evaporate from the land and sea, turning it into water vapor. There is also transpiration, which is evaporation from plants. The water vapour rises and cools and condenses into clouds. Water falls from the clouds as precipitation onto land. The water drains into the sea and the process restarts.

Question 31

How do droughts occur

Answer 31

When there isnt enough precipitation.

Question 32

Desalination

Answer 32

A method that produces potable water from salt water.

Question 33

Thermal desalination

Answer 33

Where salt water is boiled, and the steam is collected as pure water.

Question 34

Reverse osmosis

Answer 34

Osmosis is water from high to low. The higher the salt conc., the lower the water conc. Therfore osmosis is also the movement of water from an area of low salt conc to an area of high conc. Revers osmosis takes advantage of this by:
Salt water is treated to remove solids, then pushed into a vessel at a very high concentration with a partially permeable membrane. This causes the water to move in the opposite direction to osmosis. This leads water to be forced through the membrane and salts to be left behind.

Question 35

Describe the nitrogen cycle

Answer 35

Nitrogen-fixing bacteria turn nitrogen in the air into nitrates and nitrites in plants and the soil. Plants use these to make proteins. these proteins are passed on to animals that eat the plants. Decomposers then break down the proteins in rotting plants and animals and urea into ammonia, which turns into ammonium ions. This returns the nitrogen to the soil to be recycled. Denitrifying bacteria turn nitrates into nitrogen gas, and has no benefit to living organisms.

Question 36

Decomposers

Answer 36

Decompose proteins and urea and turn them into ammonia which froms ammonium ions.

Question 37

Nitrifying bacteria

Answer 37

Turns ammonia in decaying matter into nitrates and nitrates.

Question 38

Nitrogen fixing bacteria

Answer 38

Turns nitrogen in the air into ammonia which froms ammonium ions. live in soil or roots of legume plants.

Question 39

Denitrifying bacteria

Answer 39

Turns nitrates into n2 gas.

Question 40

Farmers can increase the amount of nitrates in soil by

Answer 40

Crop rotation and fertilisers

Question 41

Crop rotation

Answer 41

Different crops are grown each year. Usually involves a nitrogen-fixing crop, which put nitrates in the soil for the next crop

Question 42

Fertilisation

Answer 42

Spreading animal manure of compost on fields to provide nutrients to soil.

Question 43

How are indicator species used to show water pollution

Answer 43

If water is polluted by sewage or fertilisers, then species such as blood worms and sludgeworms indicate pollution.

Question 44

How are indicator species used to show clean water

Answer 44

If there are freshwater shrimps or stonefly, then the water is clean

Question 45

How are indicator species used to show air pollution

Answer 45

The air is clean if there is bushy lichen rather than crusty lichen. Blackspot fungus on rose leaves hows clean air.

Question 46

Rate of decompostion is dependant on:

Answer 46

Temperature, water content, oxygen

Question 47

Food preservation methods

Answer 47

Freezing lowers temperature, airtight can prevent too much oxygen availibility, and drying food removes water content.