B7- Ecology and feeding relationships

Question 1

Define these terms:

1) Ecosystem
2) Habitat
3) Community.
4) Population

Answer 1

1) Ecosystem: the interactions of a community of living organism with the non-living (abiotic) parts of their environment.
2) Habitat- place where the organism lives.
3) Community: the population of different species living together.
4) Population: all the organisms of one species living in a habitat.

Question 2

Define these terms:

1) Abiotic

2) Biotic

Answer 2

1) Abiotic: non-living factors of the environment.

2) Biotic: living factors of the environment.

Question 3

Give 7 examples of abiotic factors.

Answer 3

Abiotic factors:

• light intensity.
• temperature
• moisture levels
• soil pH and mineral content.
• wind intensity and direction.
• availability of oxygen.
• availability of Co2

Question 4

What is interdependence?

Give examples of organisms being interdependent(4)

Answer 4

• Within a community, species rely on each other for survival, food and shelter therefore if one species is removed, or becomes very numerous, it can affect the whole community.

Interdependent:

• oxpecker with the rhino
• bees pollinating plants.
• Plants produce food by photosynthesis and animals eat plants and pollinate plants.
• Animals eat other plants
• Animals use plants and animal material to build shelters.
• Plant need nutrients from animal dropping and decay.

Question 5

Define a stable community.
Give 3 examples.
What’s the issue with stable communities?

Answer 5

A stable community is one where all the species and environmental factors are in balance so that population size remains fairly constant.

• 3 examples of stable communities would be meadows, woodlands and tropical rainforest.
• The problem with a stable community is that humans disrupt this eg deforestation which displaces a ‘stable community’ and the habitats of organisms.

Question 6

What’s a parasitic organism?

What’s a mutualistic organism?

Answer 6

• Parasitic organism: feeds on another organism called a host and the host is harmed whilst the parasite benefits.
• Mutualistic organism- both organisms benefit from each other.

Question 7

Why is a predator-prey relationship important?

Answer 7

Predator-prey relationship is important because competition for food in a species is reduced and predator allows natural selection to occur- ‘survival of the fittest’ so enables us to develop characteristics and features that will allow us to survive and progress.
- it also controls the size of a species and helps keep the environmental stable

Question 8

What resources do organisms compete for? P&A (4)

Answer 8

• Plants need light, space, as well as water and nutrients( mineral ions) from the soil.
• Animals need space( territory)), water, food and mates.

Organisms compete with each other and other species for the same resources.

Question 9

How can plants be affected by a change in abiotic factor? (2)

Do animals depend on plants? ^

Answer 9

• A decrease in light intensity, temp or level of Co2 could decrease the rate of photosynthesis in a plant species and this could affect plant growth and cause a decrease in population size.
• The decrease in mineral content of the soil could cause nutrient deficiencies and could affect plant growth- causing a decrease in the population of plants.

Animal depends on the plant for food so a decrease in plant population could affect the animal species in a community.

Question 10

Why is there a delay in the fluctuations in cyclic fluctuations predator-prey graphs? (2)

What are some predators?

Answer 10

1) Time for the population to die/ grow.
2) Time is taken to reproduce and for offspring to mature.

Some predators are generalists and these predators eat a lot of different prey so they have a higher chance of survival. On a graph, the population would do little/ low change.

Question 11

List 4 biotic factors?

Answer 11

1) New predator arriving- organisms that have no defences against predators may quickly be wiped out.
2) Interspecefic Competition- one species may outcompete another so that numbers are too low to breed.
3) New Pathogens or parasites- organisms have no resistance to disease and a new pathogen can damage or even wipe out populations in a community,
4) Availability of Food- plenty of food= organisms breed successfully.

Question 12

Explain how abiotic factors affect communities:

• Light intensity. (3)
• Temp (3)

Answer 12

Light intensity:

• essential for photosy
• the higher the value, higher the success for plants.
• plants have adaptations for low levels eg large leaves or more chlorophyll

Temp:

• factor affects enzymes that control the metabolic rate.
• at a higher value, plants develop quicker due to metabolism being faster as enzymes control metabolic rate.
• endotherms are reliant on this factor but are less affected due to homeostasis

Question 13

Give 4 abiotic factors affect communities(plants)?

What are some ways plant cope with competition?(3)

Answer 13

1) Light intensity.
2) Moisture levels.
3) Temp.
4) Soil pH

1) Plants can have different types of roots- some plants have shallow roots to take minerals and water from the surface of the soil whereas others have deep roots that go underground.
2) Plants that grow in shade may grow taller to reach sunlight- it may have larger leaves or may have tendrils or suckers that allow them to climb on top of other trees
3) To avoid competition with seedlings, plants use the wind to help them spread the seeds as far as possible so they don’t have to compete for light,space, water, mineral ions. Root of some desert plants produce a chemical to stop the seeds from germinating,killing because it can grow.

Question 14

Explain how abiotic factors affect communities:

• Soil pH (4)
• Moisture level (2)

Answer 14

Soil pH

• major effect on what can grow in it and on the rate of decay therefore on the release of mineral ions back into the soil. A low acidic pH inhibits decay
• cucumber and cauliflower best grow in alkali conditions.
• factor affects the biological activity in soil and mineral content.
• fems and rhododendrons grow best in alkali conditions

Moisture level:

• the main component of blood plasma and if too little is available, animals could die.
• required to keep plant cell turgid in photosynthesis.

Question 15

Difference between interspecific and intraspecific?

Answer 15

Interspecific is competition between different species.

Intraspecific is competition among the same species.

Question 16

What are the 2 ways to study the distribution of organism?

Both methods give what?

Answer 16

• The simplest way to count the number of organisms is to use a sample area called a quadrat and measure how common an organism is in two sample areas and compare them
• Study how the distribution changes over across an area, by placing quadrats along a transect.

Both methods give quantitative data about the distribution.

Question 17

Why do organisms live in different places?

Answer 17

• because the environment varies and an organism can be affected by environmental factors and an organism might be more common in one area than another due to the differences in environmental factors between the two areas.

Question 18

Describe how to use quadrats to study the distribution of small organisms? (6)

Answer 18

1) Place a 1M^2 quadrat on the ground at a random point within the first sample area and you have to choose the sample size at random by using a random number generator which can be a more scientific way of deciding where to place the quadrat. Get 2 long tape measures out to produce an axis.
2) Use coordinates to place your quadrats. Use an identification key and Count the organisms within the quadrat.
3) Repeat steps 1 and 2 as many times as you can.
4) Work out the mean number of organisms per quadrat within the first sample area.
5) Repeat step 1-4 in the second sample are.
6) Compare the 2 means.
7) Estimate population size.

Question 19

How to work out the mean with a quadrat?

Answer 19

Total number of organisms/ number of quadrats= Mean.

Question 20

How to work out population size of an organism in one area?

Answer 20

• the number of organisms sampled
  / the area sampled
  x total area/ grid size.

Question 21

10 quadrats, each 50cm x50cm.
15m x15m grid.
- 121 daisies.

Estimate the population size

Answer 21

121- number of organisms samples.
0.5m x 0.5m x 10 quadrats - the area samples.
total area of grid= 15x15

121/ 2.5 x 225

10890 organisms/ msq

Question 22

5 quadrats, each 50cm x 50cm
Grid= 20x 20
162 daisies.

Population size?

Answer 22

162/ 1.25 x 400

=
51840 daisies/ msq

Question 23

Why would we use a transect? (3)

PAG

Answer 23

• To study the distribution of organisms along a line.
• Transects are not random.

1) Mark a line in the area you want to study using a tape measurer.
2) Collect data along the line and do this by counting all the organisms you’re interested in that touch the line. Take 5 readings and take sample ever 2m eg.
3) Or collect data by using quadrats and these can be placed next to each other along the line or at intervals to see a change in species distribution in a line from A to B.

-Transects can be used in any ecosystem, not just fields.

Question 24

What do animals compete for? (3)

What makes a successful competitor?

Answer 24

• food
• territory
• mate

A successful competitor is an animal that is adapted to be better at finding food or mate than the other members of its own species. It must also be able to breed successfully

Question 25

What are adaptations?

Answer 25

The features and characteristics that allow organisms and microorganisms to survive are called adaptations. They can be:

• Structural
• Behavioural
• Functional

Question 26

List some structural adaptations (3)

Answer 26

These are features of the body of an organism structure such as shape and colour:

1) Arctic animals- Arctic fox has white fur that helps them be camouflage- avoid predators and sneak up on prey.
2) Animals that live in cold places like whales- thick layer of blubber and a low SA to V ratio to help them retain heat.
3) Animals that live in hot places eg camels- have a thin layer of fat and large SA: V ration to help them lose heat. Have large thin eas to help the transfer energy to surroundings through their skin, cooling them down.

Question 27

List some behavioural adaptations

Answer 27

Many species eg swallows migrate to warmer climates during the winter to avoid the problem of living in cold conditions.

Question 28

List some functional adaptations(2)

Answer 28

Functional adaptations go inside the organism’s body that can be related to processes like reproduction and metabolism.

1) Desert animals conserve water by producing v little sweat and small amounts of conc urine.
2) Brown bears hibernate over winter. They lower their metabolism which conserbes energy so they don’t have to hunt when there’s not much food about.

Question 29

What adaptations do microorganisms have?

What temp can bacteria live in deep sea vents?

Answer 29

• Microorganisms such as bacteria are known as extremophiles and they’re adapted to live in v extreme conditions such as in high temp( volcanic) and live in high salt conditions(salt lakes)and high pressure eg deep sea vents.
• They live between 40-80 as their enzymes do not denature.

Question 30

List some plant examples of adaptations?(3)

Answer 30

1) Epiphyles mainly grow in rainforests- grow on other plants allowing the leaves to be able to absorb sunlight from higher pos on the trees.
- found in rainforests as there’s high moisture and humiditiy and the roots absorb this and minerals from the decaying lead litter on branches.
- upturned leaves help store water.

Question 31

List some distinctive adaptations between predator and prey. (6)

Answer 31

Predator:

• canine teeth.
• agility
• claws
• smell, hearing and sight r more acute.
• powerful binocular vision so they can judge distance and depth.
• quick reaction time.

Prey:

• monocular vision- maximise field of vision.
• camouflauge
• defence mechanism eg horns and tusks.
• hooves.
• travel in herds.
• large ears to rotate

Question 32

Define:

• producer,
• consumer
• decomposer

Answer 32

Producer- organisms that make their own food through a process of photosynthesis.

• Consumer- organisms that eat other organisms to gain energy.
• Decomposer- organisms that break down dead matter into insoluble components and organic matter such as nitrates and mineral ions

Question 33

Where do food chains usually start?

Answer 33

Food chains usually trace back to photosynthetic organisms such as green plants and algae and sunlight as their source of energy to make glucose by photosynthesis, but other food chains such as extremophiles use a diff source of energy- they can use sulphur instead of glucose from volcanoes.

Question 34

Define a food web.

Define a trophic level

Answer 34

A food web is a combination of several food chain

-Trophic level- stages in a food chain.

Question 35

How would you set out pyramids of biomass?(4)

Answer 35

1) Primary producers are level 1
2) Animals eating the primary producers are called primary consumers= level 2
3) Level 3= secondary consumers
4) Level 4- tertiary or third cos

Question 36

Define biomass? What type of biomass is usually used?

Answer 36

Biomass- the living or recently dead mass of living organism at each stage/ trophic level of a food chain.

-Dry biomass is normally used to remove excess mass because water levels can vary throughout the day and drying biomass helps remove that factor.

Question 37

In a stable community in regards to predator and prey, what happens? (4)

Answer 37

In a stable community:

1) The population of any species is usually limited by the amount of food available.
2) A population of prey increases, so will the population of the predator.
3) However, if the population of predators increase, the number of preys will decrease.

Predator-prey cycles are always out of phase with each other because it takes a while for the population to respond to change in the other populations eg when the number of rabbits go up, the number of foxes don’t go up immediately because it takes time for them to reproduce.

Question 38

Why is there a reduction of biomass in each level (5)

Answer 38

Biomass is lost:

1) Some are indigestible components eg bone, hair( egestion)
2) Respiration- energy transferred to moving.
3) Exothermic- loss of heat to the environment.
4) Excretion- faeces and urine.
5) Not all wavelengths of light are absorbed which would impact the level of photosynthesis- energy lost.

Question 39

Why would energy be lost? (3)

Answer 39

• Reproduction
• Metabolic reactions.
• Movement( Exothermic process)

Question 40

Why can the distribution of organisms change over time? (3)

What are these changes caused by?

Answer 40

A change in the:

• availability of water
• temperature
• atmospheric gases- change in areas where there is more air pollution

These environmental changes can be caused by seasonal factors, geographic factors or human interaction. For eg, the rise in the average temp is due to global warming which has been caused by human activity

Question 41

Describe the water cycle(5)

Answer 41

1) energy from the sun makes water evaporate from land and sea, turning it into water vapour. Water also evaporates from plant due to transpiration.
2) Warm water vapour carries upwards as it rises and it gets higher, it cools and condenses to form clouds.
3) Water walls from the cloud as percipitation( usually rain, snow or hail) onto land where it provides fresh water for plants and animals.
4) It then drains into the sea and whole process repeats

Water vapour passes through the bodies of animals and plants, released during respiration or when organisms decay. Animals also release water in their faeces, urine and sweat.

Question 42

How is Co2 it to be returned into the atmosphere? (4)

Answer 42

(TIONS)
1)Respiration- oxygen is used to break down glucose into energy and CO2 that is released in the atmosphere.

2) Combustion- wood from trees contain lots of Carbon locked into the molecules of the plant during photosynthesis- fossil fuels have locked up carbon as well so when they’re burnt, they release it back into the atosphere
3) Decomposition- when plants animals and algae die, animals called detritus feeders and microorganisms feed on their remains- respire- Co2 returns.
4) Egestion – the removal of faeces from an animal that will contain carbon. This egested material can be broken down during the process of decomposition.

Question 43

How can co2 be removed from atmosphere? (4)

Answer 43

1) Oceans- Co2 dissolves.
2) Photosynthesis- green plants and algae remove CO2 from the atmosphere and they use it in photosynthesis to makes carbohydrates, proteins and fats that make up their bodies.
3) Fossilisation- if conditions are not favourable for the process of decomposition, dead organisms decay slowly or not at all. These organisms build up and, if compressed over millions of years, can form fossil fuels
4) Digestion-plants and algae are eaten by animals, some carbon becomes part of the fats and proteins in their body.. The energy that green plants and algae get from photsynthesis is transferred up the food chain

Question 44

Describe the Carbon cycle? (7)

Answer 44

1) Co2 is remoed from the atmosphere - green plants and algae remove CO2 from the atmosphere and they use it in photosynthesis to makes carbohydrates, proteins and fats that make up their bodies.- photsynthesis.
2) Plants and algae respire-CO2 returns to atmosphere
3) plants and algae are eaten by animals, some carbon becomes part of the fats and proteins in their body.. The energy that green plants and algae get from photsynthesis is transferred up the food chain
4) When animals respire- Co2 returns.
5) when plants animals and algae die, animals called detritus feeders and microorganisms feed on their remains- respire- Co2 returns.
6) Animals also produce waste that is broken down by detritus feeders and microorganisms.
7) Combustion of wood and fuel also releases Co2 back in the atmosphere.
SO carbon and energy is constabtly being cycled, from the air, through food chains and eventually back out of the air again.

Question 45

Descirbe how the elements are recycled back to the start of the food chain? (5)

Answer 45

• Plants turn elements such as carbon, oxygen, hydrogen and nitrogen from the soil the air into rthe complex compounds that make up living organisms and this gets passed up the food chain.
  2) These materials are returned to enviro in waste products or when the organisms die and decay
  3) Materias decay because they’re broken down by microorganisms and happens faster in warm, moist aerobic condition
  4) Decay puts the elements back that plants need to grow ( eg mineral ions) back into soil.
  5) In a stable community, materials that are taken out of the soil and used by plants are balanced by those that are put in.

Question 46

What is compost?

Give an example?

Answer 46

-Decimposed organic matter used as a natural fertiliser for crops and gtrgvgarden plants.

Eg:

• Food waste
• Manure

Question 47

What is the rate of decay affected by? (5)

Answer 47

1) Temperature- warmer temps make things decompose quicker because they increase the rate that the enzymes involved in decomposition work at- too hot- rate decomposition slows down or stops because the enzymes have denatured and organisms die, too cold- slow rate of decomposition- KE is transferred and the quicker the particles will move and increase metabolic rate - respiration and digestion will occur faster.
2) Moisture/ Water availability- moisture makes it easy for the microorganisms to digest their fod and allows soluble molecules to be asborb, and they need water to carry out biological processes.
3) Oxygen availability- many need oxyen to respire and break down food, grow and reproduce- increased rate of decay but, many microorganisms involed in anaerobic decay don’t need oxygen.
4) Number of decay organisms- the more microorganisms and detritus deefers there are, the faster the rate of decomposition.
5) Nutrients availability- do more protein synthesis and grow and reproduce.

Question 48

Why is compost so important to farmers?(2)

Answer 48

• Farmers and gardeners try to provide ideal conditions for quick decay to make compost.
• Compost or well- rotted manure provides fertiliser for the soil, returning valuable minerals and also providing soil structure and water retention.

Question 49

Describe briefly the nitrogen cycle

Answer 49

1) Plants are the only organisms that can take up nitrates as they dissolve in water through the xylem
2) Animals get nitrogen from protein in plants and other animals- broken down to amino acids and build that to ptoduce new proteins and through protein synthesis.

Question 50

Define:

• decay
• decomposer
• detrivore

Answer 50

Decay: breakdown of organic matter.
Decomposer- microorganisms that break down organic matter eg bacteria or fungi into soluble components.
Detrivore- larger animals which eat dead matter eg worms and maggots.

Question 51

Describe what is needed for slow decomposition? (5)

If salt is a factor, what can be done to cause the bacteria to grow in an experiement?

Answer 51

• low temp
  -low oxygen- closed system
• low moisture as fungi use moisture and water for reproduction so lowers reproduction.
• Salt will decrease water potential which measn the bacteria will have a high water potential than salt and therefore bacteria loses water through osmosis and dies.
  ( move it to a new petri dish and add more nutrients- move microorganisms to keep them alive( replanting or culture)
• Nutrient level low.

Question 52

Why do worms increase the rate of decomposition?(2)

Answer 52

1) They break down dead matter which will increase the SA that decomposes.
2) Aerate- worms dig tunnels which aerate soil and allow oxygen to get further into the soil- increased decomposition.

Question 53

What usually occurs in watery condition?

Describe the process listed above? (7)

Answer 53

Eutrophication (and happens in stagnant water eg lakes and ponds)- when a body of water becomes overly enriched with minerals and nutrients which induce excessive growth of plants and algae. This process may result in oxygen depletion of the water body

1) Normally, lakes in sunshine and there is a sudden increase in nutrients ( could be due to fertilisers, manure, sewage) and algae will grow on stagnant lakes quickly ( algae bloom)

2) Competition means that organisms start to die.
3) Decomposers eg bacteria will breakdown the dead matter BY DIGESTION.
4) O2 will be used for respiration when decomposing the dead organisms.
5) Fish/ marine animals will die due to the lack of oxygen.
6) More dead matter will accuulate and decomposers break them down which is a continual process.
7) so reduced energy supply causes death of fish. toxins in the sewage can also kill fish

Question 54

Does algae kill the fish during eutrophication?

Answer 54

• No algae does not kill the fish as they photosynthesis and provide oxygen but when algae dies, bacteria breaks down the dead matter and uses dissolved O2 from the water.
• You could say that if there’s an increase in nutrients through a use of a fertiliser- that could be toxic to animals and fish may die.

Question 55

Why do size of trophic levels vary in pyramids of biomass as you go up?

Answer 55

Organisms tend to be larger in size at higher trophic levels, but their smaller numbers result in less biomass. and therefore have a smaller bar

Question 56

Explain why plants need water?(4 marks)

Describe how the plants get the water they need?

Give 3 ways as to how a plant can lose water?

Answer 56

They need water for
photosynthesis,
cell support,
tissue support,
transport of substances around plant

2) From soil, through roots.
3)- evaporation from leaf cells into air spaces,
diffusion down a concentration gradient
through stomata into the surrounding air

Question 57

Plants that live in dry conditions have adaptations to reduce water loss from their leaves. Give three of these and explain how they work (6 mark)

Give three other adaptation plants have to survive in dry conditions?

Answer 57

• curled leaves – reduced surface area, traps moist air to reduce
evaporation,
• small leaves – reduced surface area,
• thick cuticle – reduced rate of evaporation,
• stem‑like leaves – reduced number of stomata to minimise
water loss by diffusion into air.

2)extensive root system covering wide area – maximising water uptake
from soil,
long roots going very deep – maximising water uptake from soil,
water storage tissues – to store water in fleshy leaves/stems/roots after
rain

Question 58

The Indian peafowl’s diet includes seeds. At rhe some point, some of the carbon in these seed have been part of another peafowl.
Explain how the carbon could have become part of another peafowl. (4)

Answer 58

1) When the peafowl died, other animals and microorganisms have eaten its remains,
1) The carbon in the peafowl’s body the became part of these organisms.
1) When these organisms respired, the carbon would have been released into the atmosphere at CO2
1) Plants would use the CO2 to make glucose and photosyn
1) The glucose would then have been incorporated into other parts of the plants such as the seeds which the Indian peafowl eats.

Question 59

Use your ideas on biomass transfer; explain why the number of Asiatic lions will always be ;lower than the number of chital deer in the ecoystem (4)

Answer 59

1) There needs to be more chital deer to support all of the lions because not all the biomass of the deer is passed on to the lions.
1) This is because the lion won’t eat the whole chital deer.
1) Also, not all of the material that the lion ingests is absorbed as some is egested as faeces.
1) and some of the material is lost eg wasye.

Question 60

Biogas is considered as a carbon neutr source of energy and this is because the amount of CO2 it produces is the same as the amount the oganisms used to make the biogas took in when they were alive.

Explain why a widespread use of biogas as a fuel may be beneficial for global biodiversity (4)

Answer 60

Carbon neutral energy sources help to maintain stable levels of Co2 in the atmosphere(1)

(1) which may help reduce the rate of global warming
(1) This may benefit global diversity because fewer species would become extinct.
(1) as a result of being unable to survive in a diff climate.

Question 61

When a deer sees a lion, it starts running. This is called ‘fight or flight’ response. Explain how a deer’s body prepares for it to quickly run away when it sees the lion approaching (5)

Answer 61

Nerve impulses are sent from the deer’s brain to the adrenal glands(1)
These respond by secreting adrenaline into the blood(1)
Adrenaline increases the deer’s heart rate(1)
which increases the supply of oxy and glucose (1) to its brain and muscles(1) and this means the deer will be able to release more energy through respiration which allow it to run away more quickly