Unit 7 - Ecology

Question 1

What is an ecosystem

Answer 1

The interaction of a community of living organisms (biotic) with the non living (abiotic) parts of their environment

Question 2

What is a community

Answer 2

Name given to all the organisms living in the same habitat

Question 3

Name some Abiotic factors which can affect a community are

Answer 3

-light intensity
-temperature
-moisture levels
-soil pH and mineral content
-wind intensity and direction
-carbon dioxide levels for plants
-oxygen levels for aquatic animals

Question 4

Name some biotic factors which can affect a community

Answer 4

-availability of food
-new predators arriving
-new pathogens
-one species outcompeting another so the numbers are no longer sufficient to breed

Question 5

What is a population

Answer 5

All the organisms of one species living in a habitat

Question 6

Factors for which organisms are competing in a habitat for

Answer 6

Plants = light, space, water , mineral ions from soil
Animals = space(territory), food, water, mates

Question 7

How do plants / animals depend on each other

Answer 7

-Each species depend on other species for good shelter, pollination and seed dispersal
-if one species is removed it can affect the whole community

Question 8

How are organisms adapted to the conditions they live in

Answer 8

Structural = artic foxes has white fur so they’re camouflaged and can avoid predators, animals in cold places have a thick layer of blubber and low surface area to volume ratio to retain heat
Behavioural = many species migrate to warmer climates during winter to avoid cold conditions
Functional = desert animals conserve water by producing little sweat and small amounts of concentrated urine

Question 9

Features of a food chain

Answer 9

Producer = photosynthesises (usually algae or a green plant)
Primary consumer = eat producer
-secondary consumer = eat primary consumer
-tertiary consumer = eat secondary consumer, nothing eats them

Question 10

What are the environmental changes that can affect the distribution of organisms

Answer 10

-temperature
-availability of water
-composition of atmospheric gases

These changes may be seasonal, geographic or caused by human interaction

Question 11

What is the steps of the water cycle

Answer 11

-the sun makes water evaporate from the land and sea into water vapour
-water vapour rises and cools and condenses to form clouds
-water falls from clouds as precipitation onto land
-provides fresh water for plants and animals on land before draining into sea again

Question 12

What is the process of the carbon cycle

Answer 12

-CO2 is removed from atmosphere by green plants and algae during photosynthesis
-used to make glucose which can turn into fats and proteins
-when plants and algae respire CO2 is returned to atmosphere
-plants and algae are eaten by animals carbon moves through the food chain
-when animals respire CO2 is returned to atmosphere
-when plants/animals / algae die microorganisms feed on their remains and also respire releasing CO2
-plants and animal material may then be used as a fossil fuel in the future for combustion (which releases CO2)

Question 13

Factors that affect rate of decay and why

Answer 13

Temperature = warmer temperatures make decomposing quicker as they increase the rate that enzymes work, if it’s too hot decomposition slows down because enzymes are denatured and organisms die
Water availability = decay is faster in moist environments because microorganisms need water to carry out biological processes
-oxygen availability = need oxygen to respire which they need to survive, organisms involved in anaerobic decay don’t need O2

Question 14

What is compost

Answer 14

-decomposed organic matter
-used as a natural fertiliser for growing garden plants and crops
-farmers try to provide optimum conditions for rapid decay of waste biological material

Question 15

What is biogas

Answer 15

-biogas generators produce methane as a fuel
-made in a simple fermenter called a digester or a generator
-need to be kept at a constant temperature so microorganisms can respire

Question 16

What is anaerobic decay

Answer 16

-when bacteria and fungi break down dead matter without oxygen
-products are methane and carbon dioxide

Question 17

What is biodiversity

Answer 17

-the variety of all the different species of organisms on earth, or within an ecosystem
-A great biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment.

Question 18

Why is human population increasing

Answer 18

-modern medicine and farming methods as they have reduced number of people dying from disease and hunger

Question 19

Ways in which pollution can occur

Answer 19

-in water= sewage and toxic chemicals from industry pollute lakes affecting plants and animals, chemicals used on land (fertilisers, pesticides ) washed into water
-on land = toxic chemicals used in farming (pesticides ), bury nuclear waste in landfill sites
-in air = smoke and acidic gases released (sulfur dioxide can cause acid rain )

Question 20

Effect of pollution

Answer 20

Kills plants and animals so reduced biodiversity

Question 21

Consequences of global warming

Answer 21

-sea levels rising = ice caps melting, leads to flooding of low lying areas
-changes in species distribution = may change as temperature and amount of rainfall changes
-changes in migration patterns
-reduction in biodiversity = species are unable to survive so become extinct

Question 22

Impacts of destruction of peat bogs

Answer 22

-destroys habitats and therefore biodiversity decreases
-decay or burning of peat releases carbon dioxide into the atmosphere leading to global warming
-when drained microorganisms start to decompose it and they respire releasing CO2

Question 23

What are peat bogs

Answer 23

Bogs are areas of land that are acidic and waterlogged, plants that live in bogs don’t fully decay when they’re die as there isn’t enough oxygen, the partly rotted plants build up to form peat

Question 24

Humans reduce the amount of land available for other animals and plants by ……

Answer 24

Building , quarrying, farming and dumping waste

Question 25

2 reasons for large scale deforestation

Answer 25

-provide land for cattle farming or rice fields -grow crops for biofuels

Question 26

Impacts of deforestation

Answer 26

-cutting down loads of tress means less carbon dioxide removed by photosynthesis -carbon dioxide is released when tress are burnt -biodiversity may be reduced as less habitats for them

Question 27

Programmes to reduce the negative effects of humans on ecosystems and biodiversity and what they do

Answer 27

-breeding programmes = prevent endangered species becoming extinct, animals are bred in captivity and then released into the wild -habitat protection = programmes to protect and regenerate rare habitats like coral reefs, protecting habitats protects species that live there -preventing global warming = regulations and programmes to reduce the level of deforestation and carbon dioxide being released -reducing waste = people,encouraged to recycle to reduce amount of waste in landfill

Question 28

What are the conflicting pressures on maintaining biodiversity and why

Answer 28

-costs of programmes = costs a lot of money, for example costs money to keep a watch on whether the programmes and regulations are being followed, conflict bewteeen protecting biodiversity and saving money -effect on local economy= for example reducing the amount of deforestation is good for biodiversity but people who were employed in tree felling industry now are unemployed -protecting food security = certain organisms are seen as pests to farmers and are killed to protect crops so more food produced, but food chain could be affected -development of society= land is in such high demand with high biodiversity has to be used for development, for example new housing developments

Question 29

What are tropic levels

Answer 29

Different stages of a food chain, they are represented by numbers starting at level 1

Question 30

What are all the tropic levels (named) and what they do / consist of

Answer 30

-level 1 : plants and algae make their own food by photosynthesis and are called policiers -level 2 : herbivores eat plants/ algae and are called primary consumers -level 3 : carnivores that eat herbivores are called secondary consumers -Level 4 : carnivores that eat other carnivores are called tertiary consumers

Question 31

Role of decomposers

Answer 31

-such as bacteria or fungi break down dead plant and animal matter -they do this by secreting enzymes into the environment -small soluble food molecules then diffuse into the microorganism

Question 32

What are pyramids of biomass

Answer 32

-represent the relative amount of biomass in each level of a food chain (how much all organisms at each level would weigh if you put them all together ) -so one fox would have a big biomass and hundreds of fleas would have a small biomass -bar at the bottom represents producer, next bar represents primary consumer and then secondary consumer and so on

Question 33

Why is biomass between the levels lost

Answer 33

-only 1% of energy from light is converted for photosynthesis by plants and algae -only 10% of biomass from each trophies level is transferred to level above it This is due to: -organisms don’t always eat every single part of the organism they’re consuming -not all the ingested material is abrobed some is egested as faeces -some absorbed material is lost as waste such as carbon dioxide and water in reparation and water and urea in urine

Question 34

How to calculate the efficiency of biomass transfer between trophic levels by percentages

Answer 34

Efficiency = (biomass transferred to next level / biomass available at previous level )x100

Question 35

What is food security

Answer 35

Having enough food to feed a population

Question 36

Factors which are threatening food security

Answer 36

-increasing birth rate (world population increasing ) -changing diets in developed countries means scarce food resources are transported around the world -new pests and pathogens are killing crops and livestock -environmental changes such as lack of rain means more famine -high costs of agricultural inputs is too eco dive for people to start or maintain food production -conflicts have arisen in some parts of the world

Question 37

Why are sustainable methods needed

Answer 37

-enough food can be made to feed everyone now and in the future -sustainable production can be used as this ensures that enough food is made without using resources faster than they renew

Question 38

Ways fish stocks can be maintained

Answer 38

-limits on the number and size of fish that can be caught in certain areas so prevents overfishing -different limits of the mesh size of fish net, so unwanted species can escap, and younger fish will slip through the net

Question 39

How can efficiency of food production be improved

Answer 39

-limiting the movement of livestock and keeping them in temperature controlled environments so reduced transfer of energy from livestock to environment -so more mergers is available for growth so more food produced -could be fed high protein diet to further increase growth

Question 40

How is bacteria genetically engineered to make human insulin (the process )

Answer 40

-plasmid is removed from a bacterium -insulin gene is cut from human chromosome using a restriction enzyme -the plasmid is cut open using the same restriction enzymes -plasmid and human insulin gene are mixed together -lipase is added this join the sticky ends of plasmid and DNA strands together -this is inserted into a bacterium -the modified bacterium is grown under controlled conditions in. vat -insulin can be harvested and purified to treat people with diabetes

Question 41

How could genetically modified crops help

Answer 41

-can be more resistant to crops so I roiled crop yield -modified to grow bette in drought conditions also improving crop yield -modified to provide more nutritional value like golden rice

Question 43

Disadvantages of biotechnology in increasing yield of crops

Answer 43

-people argue that people go hungry because they can’t afford to buy food not because there isn’t any food about -countries may become dependant on companies who sell GM seeds -poor soil is the reason crops fail and even GM crops won’t survive