B4 Ecosystems

Question 1

Producers

Answer 1

Organisms that make their own food by photosynthesis (plants/algae)

Question 2

Consumers

Answer 2

Organisms that can’t make their own food, have to eat other organisms to gain energy (all animals)

Question 3

Decomposers

Answer 3

Special group of consumers, gain energy by feeding on dead/decaying material

Question 4

How is energy transferred to producers

Answer 4

• energy from sun transferred by light to chlorophyll in cells of producer
• photosynthesis takes place here (co2 & h2o react to make glucose)
• glucose stores energy within its chemical bonds
• glucose can be converted into carbs, fats, proteins: used as energy stores, growth, repair

Question 5

Biomass

Answer 5

= mass of living material present (increases as organism grows)

Question 6

How is energy transferred between organisms

Answer 6

• consumers eat producers
• when organism respires, energy stored in its food transferred in production of ATP
• organism grows & biomass increases
• process continues

Question 7

Trophic level

Answer 7

Each step in a food chain

Question 8

What do the arrows in a food chain show

Answer 8

The transfer of biomass (energy transfer) from one organism to the next

Question 9

Trophic levels of a food chain

Answer 9

• producer
• primary consumer (herbivore)
• secondary consumer (carnivore)
• tertiary consumer

Question 10

What makes food webs better than food chains

Answer 10

Food webs contain a series of interlinked food chains as most animals eat more than one type of organism

Question 11

Biotic factors

Answer 11

Living factors

Question 12

Biotic(living) factors of an ecosystem

Answer 12

Competition for:

• food
• space
• breeding partners

Question 13

Abiotic (non-living) factors

Answer 13

• light intensity
• temperature
• moisture level (rainfall)
• soil PH

Question 14

How does light intensity affect communities?

Answer 14

Light required for photosynthesis,
greater light availability = greater success/growth of plant
Plants evolve to grow successfully in different light intensities (larger leaves in low)

Question 15

How does temperature affect communities

Answer 15

• temp affects enzymes which control metabolic reactions

- warmer temp = faster metabolism = more rapid development (for plants, cold blooded animals)

Question 16

How does moisture level affect communities

Answer 16

• lack of water = death (osmosis, wilt)

- needed for photosynthesis

Question 17

How does soil pH affect communities

Answer 17

• soil pH affects biological activity & availability of certain minerals in soil
• some plants (rhododendrons, ferns) grow better in acidic soil (pH 1-6)
• some plants (cucumbers, cauliflower) grow better in alkaline soil (pH 8-14)

Question 18

What do plants need to survive

Answer 18

• light
• water
• carbon dioxide
• minerals
• space

Question 19

What do animals need to survive

Answer 19

• food
• water
• breeding partners
• space (territory)
• shelter

Question 20

Interdependence, 3 main types

Answer 20

= how different organisms depend on each other within a community

• predation
• mutualism
• parasitism

Question 21

Predation

Answer 21

= Relationship between a predator & prey species

- Size of predator population directly affects size of prey population

Question 22

Mutualism

Answer 22

= both organisms benefit from relationship
(Eg. Oxpeckers are birds that eat ticks/fleas living on buffalos skin, gain food while buffalo free from irritation/disease)

Question 23

Parasitism

Answer 23

= only 1 organisms (parasite) gains, organism it lives off (host) suffers
(Eg. Tapeworms in animals digestive system, fleas)

Question 24

What do pyramids of biomass show

Answer 24

= population at each trophic level, bar width represents no. of organisms present

Question 25

What is the general trend as you move from 1 trophic level to the next

Answer 25

- size of organisms (biomass) generally increases | - number of organisms generally decreases (except eg. oak tree)

Question 26

How to calculate biomass

Answer 26

Average dry mass of each organism x no. of organisms present = total biomass at trophic level (Organism killed & dried in a kiln)

Question 27

When is biomass lost

Answer 27

- not all of an organism is eaten - some biomass used in respiration - some parts of organism can’t be digested (hair), removed from body in faeces (egestion) - waste products produced by body lost through excretion (urine)

Question 28

How much chemical energy in a consumers food is converted to new body tissue

Answer 28

10%

Question 29

Why do very few food chains have more than 4 trophic levels

Answer 29

Not enough energy can be transferred to sustain life processes as less energy is transferred on each level

Question 30

Decomposers

Answer 30

Microorganisms (bacteria/fungi) that break down/decay - dead organic material at a microscopic level - animal waste (faeces/urine) To release nutrients which can be recycled

Question 31

Saprophytes

Answer 31

Organisms that feed on dead material (decompose)

Question 32

Detritivores

Answer 32

Small animals that speed up decomposition by shredding organic material into very small pieces to create a larger surface area for decomposers to work on

Question 33

Examples of detritivores & material they break down

Answer 33

- earthworm: leaves - woodlouse: wood - maggot: animal material

Question 34

How do decomposers release nutrients

Answer 34

- bacteria/fungi release enzymes, break down substances into organic matter - absorb soluble nutrients into their bodies, use theme for growth/energy store - bacteria/fungi may be eaten by other organisms, nutrients passed on - some nutrients released directly into soil/environment

Question 35

What conditions do microorganisms decompose materials most efficiently in

Answer 35

- warm temperatures - moist environments - aerobic conditions

Question 36

Why do temps affect rate of decomposition

Answer 36

- high temps = enzymes in microorganisms denatured, prevents decomposition/death of microorganisms - low temps = rate of enzyme-controlled reactions slow = rate of decomposition slow/rate of microorganism replication slow

Question 37

Why do moist environments affect rate of decomposition

Answer 37

- not enough water available = reactions within microorganisms slow down/prevented = reduces/stops process of decomposition

Question 38

Why do aerobic conditions affect rate of decomposition

Answer 38

- oxygen needed for microorganisms to respire | - anaerobic conditions prevent most forms of decomposition as microorganisms can’t survive

Question 39

Rate of decay equation

Answer 39

Rate do decay (g/day) = change in mass (g) / time (day)