Chapter 4

Question 1

Energy sources used in biological systems

Answer 1

energy allows matter to combine into different complex structures. It is essential for systems to work and cannot be recycled, it must be supplied continuously.

Question 2

What are the main sources of earths energy

Answer 2

Sun energy (radiant energy) and geothermal activity.

Question 3

What is geothermal activity

Answer 3

heat generated from the earths core which escapes to generate geothermal activity on the earths surface and in the ocean

Question 4

Abiotic factors of hot springs and geysers

Answer 4

lack of sunlight, extreme pressures, high temperatures and acidity. Organisms survive by using simple inorganic chemical compounds such as iron and sulfur as their source of matter and energy

Question 5

What are autotrophs

Answer 5

an organism capable of making its own food from inorganic substances using light and chemical energy.

Question 6

Another name for autotrophs

Answer 6

Producers, include Green plants, algae and certain bacteria.

Question 7

How do producers transform the suns energy

Answer 7

through photosynthesis. Plant cells have specialised organelles that are called chloroplasts that contain chlorophyll. Chlorophyll can absorb most wavelengths of light (except green). Only 10% of the trapped light goes into bonds. Energy is released when bonds are broken.

Question 8

What are heterotrophs

Answer 8

members of the community that cannot synthesise their own organic compounds from inorganic materials

Question 9

What are two examples of glucose polymers and what do they do

Answer 9

Cellulose (used to build the cell wall), and starch (used as an energy store for plants during periods of reduced sunlight)

Question 10

What is gross primary productivity

Answer 10

GPP is the total organic matter in an ecosystem made via photosynthesis

Question 11

What is Net primary productivity

Answer 11

NPP is the amount of organic matter available to herbivores

Question 12

How is NPP calculated

Answer 12

GPP - What the plants use themselves

Question 13

Primary productivity in different ecosystems

Answer 13

Not all producers can make the same amount of plant mass. Temperature can affect the rate at which chemical reaction can occur. Production of organic materials from the glucose made in photosynthesises is greater in some seasons compared to others. Oceans primary producers is not as efficient as terrestrial ecosystems because light does not penetrate deep water and nutrients are not freely available.

Question 14

What is photosynthetic efficiency

Answer 14

How well producers convert their energy during photosynthesis. This depends on the availability of raw materials and sunlight.

Question 15

How do herbivores extract energy from producers

Answer 15

consumers cannot carry out photosynthesis and thus cannot make their own energy. All animals must obtain their energy from the food they eat. Herbivores consume large amounts of plant material. They extract energy from the plant bonds through a process called cellular respiration.

Question 16

What is the use for energy in animals

Answer 16

To carry out work. Foraging for food, avoiding predators, long treks keeping warm. Bodily functions, building/repairing tissue and production of gametes in preproduction.

Question 17

What are the levels in a generalised food chain

Answer 17

Sunlight – producer – primary consumers (herbivores) – secondary consumers (second order consumers) – tertiary consumers (third-order consumers) – top carnivore

Question 18

What is the role of detritivores in an ecosystem

Answer 18

Feed on dead or decaying organic remains and waste

Question 19

What are the three types of consumers

Answer 19

Primary consumers - herbivores, feed directly on producers (plants)
Secondary consumers - carnivores, feed on primary consumers (meat)
top consumers feed on secondary consumers.

Question 20

What is trophic efficiency

Answer 20

The percentage of the energy at one trophic level that ends up at the next trophic level.

Question 21

What is the 10% rule

Answer 21

Only 10% of the energy at one trophic level is passed onto the next level. The remaining 90% is lost to its surroundings as 80% heat and 10 % chemical energy waste.

Question 22

what is a food chain

Answer 22

one organism occupying a trophic level is consumed by the next organism in a higher trophic level, creating a chain whereby energy and matter are passed to progressively higher levels

Question 23

What is a food web

Answer 23

Food web is a diagram that shows how different organisms feed on each other, thereby transferring energy through an ecosystem; interconnecting food chains in an ecosystem.

Question 24

Pyramid of number

Answer 24

Shows numbers of organisms at each level, usually a drop at each level and can be inverted. E.g. when one large producer supports lots of consumers

Question 25

Pyramid of biomass

Answer 25

Total mass of organisms measured at each level. Can be at a particular time or over a year. Usually pyramid. e.g when photo synthesizers are small with short life span.

Question 26

Pyramid of Energy

Answer 26

A representation that shows the rate at which energy is transferred from one trophic level to another in a given area of a ecosystem

Question 27

How are nutrients returned to soil

Answer 27

Nutrients essential for plant growth are taken from the soil by a network of plant roots. Micro organisms in the soil and on the surface contribute to the decay of plant matter such as leaf litter. Nutrients also Exeter the soil in rainfall. An obstacle in the nutrient cycle is ow quickly nutrients can be returned to the soil from the decomposition of dead organic matter

Question 28

Carbon cycle

Answer 28

Autotrophs take in carbon dioxide from the atmosphere and carbon dioxide is released through respiration and combustion. Remains of organisms for fossil fuels under high pressure and long periods of time.

Question 29

What are carbon sources. Give 3 examples

Answer 29

the origin of materials deposited in the sink. emissions from burning fossil fuels, forest fires, and respiration.

Question 30

What are carbon sinks. Name 3

Answer 30

a reservoir of material or energy. Eg, Ocean, plants and soil

Question 31

Nitrogen cycle

Answer 31

Nitrogen is essential for living things to make proteins essential for plant structure and function. Nitrogen is converted to nitrates by specialised bacteria. Nitrogen is returned to atmosphere by volcanic activity and bacterial conversion of nitrates to nitrogen.

Question 32

how do plants get nitrogen

Answer 32

Plants cannot absorb nitrogen directly from the atmosphere, most plants can only absorb the dissolved form of nitrates. Fixers, nitrifiers and denitrifies are specialised bacteria that live in root organs called nodules. In exchange plants have a ready source of nitrogen.

Question 33

What is nitrogen fixation

Answer 33

Process when free nitrogen is fixed to form ammonium and nitrate ions so that living things can use it

Question 34

What are ammonifiers and what do they convert

Answer 34

Bacteria and fungi, convert waste into ammonia

Question 34

What are nitrifiers and what do they convert

Answer 34

Bacteria, convert ammonia into nitrites and nitrites into nitrates

Question 35

What are denitrifiers and what do they convert

Answer 35

Bacteria, nitrates into nitrogen

Question 36

What are nitrogen fixers and what do they convert

Answer 36

Nitrogen into ammonium ions

Question 37

Phosphorus cycle

Answer 37

Phosphorus gets buried in rocks by volcanic activity and earthquakes. Weathering releases phosphates to soil and water entering the food chain through plants. Can be returned to abiotic reservoirs as calcium phosphates in bone, shells hard parts of aquatic animal.

Question 38

Biological magnification

Answer 38

The concentration of non-biodegradable substances such as DDT and mercury can be increased as they get passed from one trophic level to the next on a food chain. May not affect organisms lower in the food chain but can be disastrous to the top of the food chain. For example, reproduction rates could decline and death rates could rise.

Question 44

What is humus

Answer 44

the organic matter found in soil. Stores nutrients, contributes to soil texture and water holding capacity

Question 45

what are the two criteria a region must meet to qualify as a biodiversity hotspot

Answer 45

Must have a high percentage of plant life found nowhere else on the planet.
It must have 30% or less of its original natural vegetation. (must be threatened)

Question 46

human impact on nitrogen and phosphorus cycle

Answer 46

too much fertiliser in soil, soil cant absorb, water washes excess nutrients into river systems. algae use nutrients which leads to eutrophication

Question 47

human impact on carbon cycle

Answer 47

Urbanisation, deforestation, Factory emissions, car emissions