Section 8&9

Question 1

Exchange of materials

Answer 1

Organisms exchange substances with their environment - they take in substances they need and get rid of waste
Cells need oxygen for respiration with produces co2 - moves between cells and environment through diffusion
How easy it is for an organism to exchange substances with its environment depends on organisms
Surface area:volume ratio

Question 2

How does urea diffuse

Answer 2

Diffuses from cells to blood plasma for removal by kidneys

Question 3

Specialised exchange surfaces - the alveoli

Answer 3

Multicellular organisms need exchange surfaces
Gas exchange in mammals happens in the alveoli

The alveoli are adapted for efficient gas exchange- thin walls - big surface area-good blood supply-moist lining for dissolving gasses

Question 4

Circulatory system - blood

Answer 4

Red blood cells - Carry oxygen
No nucleus
Large surface area - biconcave
White blood cells - fight infection
Large nucleus 
Platelets- clot blood around wounds
Plasma- liquid - carries everything except oxygen

Question 5

Circulatory system- blood vessels

Answer 5

Artery- carry blood away from heart - thick muscle and elastic to withstand high pressure

Vein- carry blood into heart - thinner muscle and elastic - valves prevent backflow

Capillaries- carry blood into muscle and tissue - 1 cell thick, large surface area , gas exchange

Question 6

Circulatory system

Answer 6

Rv, pa, lung, pv, la, lv, a, body, vc, ra
Left side - thicker as blood goes all over body - oxygenated
Right side - thin as goes to lungs - deoxygenated

Ca= sv X hr
Cats outside ‘are’ sometimes very happy running

Question 7

Respiration

Answer 7

It’s the process of transferring energy from the breakdown of organic compounds- energy used for contracting muscles, maintains steady body temp, metabolic processes

It’s an exothermic reaction

Cellular respiration releases energy

Measure rate of respiration using a respirometer

Question 8

Aerobic respiration

Answer 8

Needs lots of energy

Glucose + oxygen -> carbon dioxide + water

Question 9

Anaerobic respiration

Answer 9

Doesn’t use oxygen

Glucose -> lactic acid(Cramps)

Glucose –> ethanol + carbon dioxide

Question 10

EcosystemsAnd interactions between organisms

Answer 10

Ecosystems are organised into different levels – individual – population – community – ecosystem
Organisms in the community are interdependent
Environmental changes affect communities in different ways – abiotic and biotic
Use quadrat to see distribution of small organisms use belt transects to study distribution along the gradient

Question 11

Abiotic

Answer 11

Temperature, light intensity, pollution, water announce

Nonliving factors

Question 12

Biotic

Answer 12

Food source, predators, bacteria, competition with other Species

Question 13

Eutrophication

Answer 13

Fertiliser spread on fields
Rain washes it into lakes/rivers
Rapid plant growth
Blocks sunlight and plants at bottom die
Decomposes/bacteria feed on decaying matter using up oxygen
No oxygen means wildlife in rivers/lakes will die

Question 14

Human impact on biodiversity

Answer 14

Eutrophication
Fish can be found in holding nets in open water
Introduction of non indigenous Species reduces biodiversity

Biodiversity is the range of species in an area

Question 15

Conservation and biodiversity

Answer 15

Managing biodiversity has many benefits – protect human food supply, providing future medicines, eco-tourism, provide new jobs, cultural aspects

National parks, zoos and artificial habitats protect at risk species

Reforestation can increase biodiversity in deforested areas

Question 16

Carbon cycle

Answer 16

Green plants use carbon from carbon dioxide to make carbohydrates fats and proteins – eating passes carbon compounds implant to animals in the food chain – both plant and animal respiration releases carbon dockside back into air – plants and animals eventually die and decompose - decomposes break them down and release carbon dioxide back into air by respiration-some useful comments and animal products are burned (combustion

Question 17

Water cycle

Answer 17

Evaporation
condensation
precipitation
water flows underground

Question 18

Cleaning water – potable

Answer 18

Desalination – are used to produce water salts from salt (distillation is away)
filter, sunlight, chlorine tablets
Reverse osmosis – used as a Modern method of discrimination – gets rid of impurities in water – salt water filtered then fed at very high pressure into a vessel containing a partially permeable membrane and pressure causes water molecules to move from high to low, as water is forced through, salt is left behind

Question 19

Nitrogen cycle

Answer 19

1. nitrogen fixing bacteria - nitrogen –> nitrates - found in roots of lagooms – (mutualistic relationships)
2. Decomposers – nitrates –> ammonium compounds
3. Nitrifying bacteria -turn ammonia into nitrites then nitrates
4. Denitrifying bacteria - nitrates are converted into nitrogen (often found in waterlogged soils)

Question 20

How can farmers increase the amount of nitrates in the soil

Answer 20

Crop rotation – instead of growing same crop in the field every year, different crops are grown in a cycle which includes nitrogen fixing crop which helps to put nitrates back into the soil for another crop to use
Fertilisers – recycles nutrients left in plant and animal waste on attendances soil through decomposition