Y9

Question 1

What are the food tests for:
1. Carbohydrates (starch & reducing sugars)
2. Proteins
3. Lipids

Answer 1

1. a) Add iodine solution: turns blue-black
   b) Add Benedict’s solution, place in a 95 degrees water bath: turns cloudy orange/brick red
2. Add biuret regent(copper sulfate & sodium/potassium hydroxide): turns purple
3. Add ethanol & water, mix: turns cloudy/milky

Question 2

What happens to carbohydrates in the digestive system?

Answer 2

Digested by: Carbohydrase
Becomes: Glucose

Question 3

What happens to proteins in the digestive system?

Answer 3

Digested by: Protease
Becomes: Amino Acids

Question 4

What happens to lipids in the digestive system?

Answer 4

Digested by: Lipase
Becomes: Glycerol and three fatty acids

Question 5

What is the difference between eukaryotic & prokaryotic cells?

Answer 5

Eukaryotic cells (found animals, plants, fungi etc.) have a nucleus and other membrane-bound organelles.
Prokaryotic cells (found in bacteria) don’t have a true nucleus, and don’t have membrane-bound organelles.

Question 6

What are some specialisations of plant cells?

Answer 6

Root hair cell: no chloroplasts, root hairs to increase surface area
Guard cell: cell membrane becomes swollen with water, stomata opens to allow for gas exchange
Palisade cell: lots of chloroplasts placed on the perimeter, a large vacuole

Question 7

What are the seven food groups?

Answer 7

Carbohydrates (provide energy)
Proteins
Lipids (fats + oils)
Vitamins
Minerals
Fibre
Water

Question 8

What are small and complex sugars (carbohydrates)?

Answer 8

Simple(monosaccharide): glucose, fructose,
Complex(polysaccharide): starch,
Small, simple sugars can combine to create complex sugars (e.g glucose + fructose = sucrose, a disaccharide).
They are made up of carbon, hydrogen & oxygen.

Question 9

What is protein needed for?

Answer 9

Required for growth and repair, antibodies in white blood cells. Also to make enzymes and other parts of cells, muscles are largely made of protein.
They are made up of carbon, hydrogen, oxygen, nitrogen (and sulfur).

Question 10

What are lipids used for?

Answer 10

To make cell membranes, to surround and protect the organs, helps the nerves to work.
They contain carbon, hydrogen & oxygen.
They are made up of 3 fatty acids and glycerol.

Question 11

What are the different types of vitamins?

Answer 11

Vitamins are compound molecules which help the body to work correctly. They keep us fit, healthy and in good condition.
Vit A: healthy eyes & skin
Vit C: healthy skin, gums & immune system
Vit D: healthy bones & teeth

Question 12

What minerals are there?

Answer 12

Calcium, magnesium, potassium & iron.

Question 13

Fibre & Water

Answer 13

Fibre: plant material, indigestible, forms the bulk of faeces, helps prevent constipation and colon cancer.
Water: all biological reactions happen in solution (contains water), 60-80% mass of a living organism is water.

Question 14

What are pyramids of number, biomass and energy?

Answer 14

Pyramids of numbers show how many of each organism there are at each trophic level.
Pyramids of biomass show how much dry mass of each organism there is at each trophic level (so it is more accurate).
Pyramids of energy show the energy of the living organisms at each trophic level.

Question 15

What are food chains and food webs?

Answer 15

Food chains are the transfer of energy/biomass from organism to organism in an ecosystem.
Chains: single routes of energy/biomass flow
Webs: many food chains put together

Question 16

How can energy be ‘lost’ (not able to be passed onto a consumer) in a food chain?

Answer 16

1. Energy used for growth & repair.
2. Energy lost to the organism as waste.
3. Energy used to make indigestible materials (bones & teeth).

Question 17

What is the structure of the heart?

Answer 17

https://docs.google.com/document/d/1276y5P-knt7h5v-MpAkUhZ5aiB1RNJj7Zb_BLI21JV8/edit?mode=html&tab=t.swjbc08zaz6d

Question 18

How does the heart pump blood around the body?

Answer 18

1. Blood flows into right atrium, the valves open and blood flows into the right ventricle.
2. The right ventricle pumps the blood through the pulmonary artery through to the lungs.
3. Oxygenated blood flows into the left atrium from the pulmonary vein, and then into the left ventricle.
4. The left ventricle pumps the blood through the aorta to the rest of the body.
   The valves ensure one way blood flow.

Question 19

Arteries

Answer 19

• carry blood away from the heart
• thick, muscular, elastic walls
• carry blood at a high pressure
• always carries oxygenated blood (except pulmonary artery)

Question 20

Veins

Answer 20

• carry blood to/in the heart
• thin, tough, less muscular walls
• carry blood under low pressure
• always carries deoxygenated blood (except pulmonary vein)

Question 21

Capillaries

Answer 21

• carries blood all over the body
• one-cell-thick walls
• oxygen, nutrients and materials diffuse through the walls

Question 22

What is a vaccine?

Answer 22

It contains dead/weakened pathogens or the antigens from the pathogen. These stimulate our lymphocytes to produce special proteins called antibodies that fight the disease.

Question 23

What is active and passive immunity?

Answer 23

Active: immunity developed by obtaining the disease and produces their own antibodies to fight it. (can be getting the disease or being injected with dead/inactive version of microbe)
Passive: immunity granted through vaccination with ready-made antibodies.

Question 24

What is the equation for magnification?

Answer 24

magnification level = image size / actual size

Question 25

What is random sampling?

Answer 25

When you use a pice of equipment called a quadrat to help you estimate the numer of organisms in an area, when it is too impractical to count them all.

Question 26

What is chemical digestion?

Answer 26

- uses certain enzymes - breaks down nutrients - occurs in the mouth, stomach and small intestine

Question 27

What is mechanical/physical digestion?

Answer 27

- food is physically broken down - chewing, churning, segmentation - moves food to mix it with digestive juices - muscles used to push food through the digestive system

Question 28

Experiment of enzymes & temperature (trypsin)

Question 29

How does temperature affect the rate of reaction of the enzymes?

Answer 29

If the temperature is less than the optimum, then there is not enough kinetic energy (the molecules move slower and the substrate and enzyme molecules react slower). If the temperature is more than the optimum, then the enzyme starts to denature (the enzyme changes shape and the substrate no longer fits in the active site.) The optimum pH also affects the rate of reaction.

Question 30

What enzymes break down what?

Answer 30

Amylase - starch into simple sugars Pepsin - proteins into amino acids

Question 31

How does the stomach help with digestion?

Answer 31

- mashes food into a watery paste called chyme - lining produces gastric juice, which contains water, HCl(kills microbes and provides optimum pH for pepsin), and pepsin

Question 32

How does the small intestine help with digestion?

Answer 32

- lining produces enzymes - pancreas adds more enzymes - optimum pH of 6-8

Question 33

How does the liver help with digestion?

Answer 33

- liver produces bile salts (stored in gallbladder) - pancrease produces sodium bicarbonate - sodium bicarbonate and bile salts are alkali, so they neutralize the stomach acid

Question 34

Why does bile increase the rate of reaction?

Answer 34

Fats are insoluble and enzymes like lipase can only digest the fat at the surface of the fat droplets. But adding bile salts causes the fats to emulsify in water, forming tiny droplets called micelles which stay suspended in water. This massively increases the surface area the lipase enzymes can work on.

Question 35

What is diffusion?

Answer 35

The net movement of particles from an area of high concentration to an area of low concentration. The motion of the particles is random. Diffusion will happen until all particles are equally spread out. It is a passive process(does not reqire energy).

Question 36

What is osmosis?

Answer 36

The movement of water from an area of high water concentration to an area of low water concentration (dilute to concentrated solution). This can only occur through a partially permeable membrane.

Question 37

What is active transport?

Answer 37

The movement of particles from a low concentration to a high concentration. It requires energy (movement against a concentration gradient). It uses energy from respiration.