Unit 1B

Question 1

Micro-organism

Answer 1

Very tiny organisms that can only be seen in detail with a microscope.

There are 4 types - bacteria, fungi, viruses and protists

Question 2

Unicellular

Answer 2

A single celled organism

Question 3

Properties of micro-organisms

Answer 3

Grow rapidly

Have simple nutrient requirements

Produce a wide range of useful products

Question 4

Conditions for growing microbes

Answer 4

Food supply

Warmth

Water

Correct pH

Question 5

Yeast

Answer 5

A single celled fungus used in brewing and baking.

Question 6

Baking

Answer 6

Yeast feeds on sugar in the dough and produces carbon dioxide gas.

This gets trapped in the dough and causes it to rise.

Question 7

Brewing

Answer 7

Yeast is used to ferment the sugar in hops and barley into alcohol and carbon dioxide (which makes the beer fizzy).

Question 8

Wine making

Answer 8

Yeast is used to ferment the sugar in crushed grapes into alcohol.

Question 9

Fermenter

Answer 9

Large container used to produce beer in commercial quantities, in carefully controlled condidtions.

Question 10

Batch processing

Answer 10

All the ingredients are placed into the fermenter at the start of the process, and it is emptied out when ready.

Used to brew beer.

Question 11

Making yoghurt

Answer 11

Yoghurt bacteria are added to sterilised milk that has been heat treated so that it contains no bacteria.

It is placed in an incubator to keep it warm.

The yoghurt bacteria feed on the lactose sugar in the milk and turn it to lactic acid.

The increased acidity thickens and sours the milk to make yoghurt.

Question 12

Biofuel

Answer 12

A renewable fuel made from plant or animal waste by fermenting it using bacteria.

Can be used for transport, heating or generating electricity.

eg. bioethanol (corn starch), biodiesel (waste oil), biogas (manure or food waste).

Question 13

Sewage treatment

Answer 13

The sewage is screened and allowed to settle to separate the liquid and solid sludge.

The sludge is stirred and aerated (air is bubbled through it) allowing bacteria to grow on it and break it down.

The liquid part is filtered through gravel containing bacteria which break down the fine sewage particles.

Treated water is returned to the river.

Question 14

Bioremediation

Answer 14

Using micro-organisms to break down harmful waste into less harmful products.

eg. sewage treatment, using bacteria to break down nuclear waste and using fungi to break down nerve gas.

Question 15

Photosynthesis

Answer 15

The process that green plants use to make food (sugars).

Question 16

Chloroplasts

Answer 16

Tiny structures inside plant cells that contain chlorophyll.

Question 17

Chlorophyll

Answer 17

The green pigment found inside chloroplasts that is used to capture light energy.

Question 18

Captured light energy

Answer 18

Splits water into oxygen and hydrogen, and is converted to chemical energy.

Oxygen is released as a waste product.

Hydrogen combines with carbon dioxide to make sugar in an enzyme-controlled reaction.

Question 19

Photosynthesis equation

Answer 19

carbon dioxide + water ——————> glucose + oxygen

Question 20

Starch

Answer 20

Made by joining glucose molecules together using phosphorylase enzyme.

Used to store the products of photosynthesis.

Question 21

Iodine

Answer 21

Used to test for starch. Turns blue-black if starch is present.

Question 22

Variegated leaf

Answer 22

A leaf with green and white areas.

Only the green areas contain chlorophyll.

Question 23

Limiting factor

Answer 23

A factor that limits the rate of photosynthesis when it is short supply.

There are 3 limiting factors : light intensity, temperature and carbon dioxide concentration.

Question 24

Greenhouse/polytunnel

Answer 24

Allow conditions to be controlled to increase the rate of photosynthesis.

This makes the plants grow faster.

Light, carbon dioxide and temperature can be controlled and plants can be protected from the wind. Greenhouses are naturally warmer, as heat is trapped by the glass.

Question 25

Pond plant experiment

Answer 25

Used to measure the rate of photosynthesis. The oxygen released by the plant can be collected and measured to study the rate of photosynthesis in different conditions.

Question 26

Respiration

Answer 26

The release of energy from food molecules (sugars) that were made by plants in photosynthesis. Happens in all cells. The energy is used for cell division (for growth and repair), building (synthesis) of large molecules, muscle contraction and transport of materials in cells.

Question 27

Digestive system

Answer 27

Food is eaten and digested into small molecules in the digestive system. Small molecules pass through the small intestine walls into the blood and are transported to cells.

Question 28

Aerobic respiration

Answer 28

Molecules are fully broken down in the presence of oxygen, releasing lots of energy. glucose + oxygen --------------------------> carbon dioxide + water + energy

Question 29

Anaerobic respiration (fermentation)

Answer 29

Molecules are partially broken down in the absence of oxygen, to release a little energy. glucose --------------------------> lactic acid + energy (animals - during vigorous exercise) glucose -----------------------------> ethanol + carbon dioxide + energy (plants and yeast)

Question 30

Limewater

Answer 30

Used to test for the presence of carbon dioxide. Turns from clear to cloudy.

Question 31

Germinating peas

Answer 31

Peas that have started to respire and grow. They give off heat that can be measured with a thermometer. Dead peas act as a control (comparison) - they don't produce heat as they are not respiring.

Question 32

Lactic acid

Answer 32

Produced as a result of the partial breakdown of sugar in animals, in the absence of oxygen (anaerobic respiration). Produced during vigorous exercise eg. sprinting.

Question 33

Recovery period

Answer 33

After vigorous exercise has stopped, oxygen is used to breakdown lactic acid.

Question 34

Percentage change

Answer 34

Work out the difference between 2 numbers, divide by the 1st one, then multiply by 100

Question 35

Enzymes and respiration

Answer 35

Respiration is an enzyme controlled reaction, so is temperature dependent. It is slow at low temperatures, increases to an optimum temperature then decreases again as enzymes are damaged by heat.

Question 36

Controversial procedures

Answer 36

People have different views as to whether certain advances in biology, such as genetic engineering are morally acceptable or not.

Question 37

Embryonic stem cells

Answer 37

Embryos are made of a ball of cells called embryonic stem cells. To use them for medical treatments, the embryo must be destroyed. This is why their use is controversial.

Question 38

Herbivore

Answer 38

An animal that eats plants to obtain food molecules.