biology

Question 1

recall the following reagents and their colour changes

Benedict’s
Iodine solution
Biuret
Ethanol

Answer 1

Benedict’s Blue —> Brick red precipitate
Iodine solution Yellow–brown —> Blue–black
Biuret Blue —> Lilac/Purple
Ethanol Colourless —> White emulsion

Question 2

Equation for
respiration

Answer 2

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

C6H12O6 + 6O2 —-> energy + 6CO2 + 6H2O

Question 3

Aerobic and
anaerobic
respiration

Answer 3

in mammalian muscle
glucose —> energy + lactic acid

and in yeast
glucose —> energy + alcohol + carbon dioxide

Question 4

demonstrate knowledge and understanding
respiration

Answer 4

reaction that is exothermic, taking
place in mitochondria, continuously releasing energy
in all cells that organisms can use for heat, movement,
growth, reproduction and active uptake/transport

Question 5

what is photosynthesis

Answer 5

endothermic process that takes
place in chloroplasts, where chlorophyll absorbs light
energy and produces sugars and starch;

Question 6

the word equation for photosynthesis

Answer 6

Carbon dioxide + water + (light energy) —> glucose + oxygen

Question 7

the balanced chemical equation for photosynthesis

Answer 7

6CO2+6H2O→C6H12O6+6O2

Question 8

what is required for photosynthesis

Answer 8

light, carbon dioxide and chlorophyll

Question 9

Photosynthesis Limiting factors

Answer 9

temperature, light intensity and
carbon dioxide concentration

Question 9

how the relationship between photosynthesis
and respiration affects the gas exchange between
organisms and their environment

Answer 9

the colour changes of
hydrogencarbonate indicator (high CO2 – yellow,
normal CO2 – red and low CO2 – purple)
* compensation point

Question 10

Eutrophication is

Answer 10

Eutrophication

Eutrophication is a type of water pollution caused by the addition of sewage or fertiliser.

Question 11

How do plants absorb minerals

Answer 11

plants absorb minerals from the soil through root
hair cells by active uptake/transport

Question 12

Carbon cycle is

Answer 12

Photosynthesis -> Respiration -> Combustion (burning)
Carbon dioxide -> Glucose -> Fuel
Glucose -> Carbon dioxide -> Carbon dioxide

Question 13

Nitrogen fixation is

Answer 13

Nitrogen gas is converted into
nitrates

This is carried out by nitrogen fixing bacteria.
Nitrogen fixing bacteria need oxygen as they are
aerobic

This process is quickened by the presence of oxygen and higher temperatures.

Question 14

Process of Decomposition

Answer 14

Bacteria/fungi break down protein found in dead plants and animals, urine and faeces into ammonia.

Question 15

What is phototropism

Answer 15

phototropism
* auxin produced at the tip of the shoot;
* auxin moving down the shoot;
* light causing uneven distribution of auxin; and
* auxin causing cell elongation, which results in
bending of the shoot.

Question 16

what is diabetes

Answer 16

• diabetes is a condition in which the blood glucose
  control mechanism fails

Question 17

what is type 1 diabetes

Answer 17

pancreas stops producing insulin, which then has to
be taken as medication throughout life
* Type 1 diabetes usually occurs early in life

Question 18

what is type 2 diabetes

Answer 18

• Type 2 diabetes is when the pancreas
  gradually produces less insulin, which in early
  stages means it can be controlled by diet but later
  may also require insulin injections;

Question 19

symptoms of diabetes

Answer 19

• the symptoms of diabetes include high blood
  glucose, glucose in the urine, lethargy and thirst

Question 20

• the number of people with diabetes in the
  population is rising and evaluate why

Answer 20

obesity is closely linked to the increasing prevalence of diabetes

Question 21

explain the structure of central nervous system

Answer 21

the brain and
spinal cord together form the central nervous system
that controls and co-ordinates the responses between
the receptors and effectors, and muscles;

Question 22

Reflex arc

what is a reflex arc

Answer 22

The nerve pathway followed by a reflex action is called a
reflex arc.
For example, a simple reflex arc happens if we accidentally touch something hot.

Question 23

what is active uptake

Answer 23

active uptake/transport is a process that requires
energy from respiration to transport the minerals
against a concentration gradient;

Question 24

Explain the steps for The starch test

Answer 24

1. Place the leaf in boiling water for 30 seconds - this kills it, stopping any
   further chemical reactions.
2. Place the leaf in boiling ethanol 0 - removes the chlorophyll making the
   leaf paler in colour.
3. Dip the leaf in water - this softens it.
4. Spread the leaf onto a white tile and add iodine 0 to test for the presence
   of starch.

Results:

If starch is present the iodine will change from yellow-brown to blue-black. If starch is absent the iodine will remain yellow-brown.

Question 25

Explain the sewage run-off in eutrophication

Answer 25

The sewage or fertiliser run-off increases the nitrate concentration of the water and has a negative effect on the aquatic
ecosystem

Question 26

Name the small pores on the surface of a leaf that allow gases to enter.

Answer 26

Stoma or Stomata

Question 27

Describe the function of the intercellular air spaces in a leaf.

Answer 27

movement of gases

Question 28

factors that affect the rate of enzyme activity

Answer 28

pH;
temperature;
enzyme concentration;
substrate concentration

Question 29

Stages of nitrogen cycle

Answer 29

1. Nitrogen-fixation
2. Feeding
3. Production of nitrogenous waste products
4. Decomposition
5. Nitrification
6. Uptake of nitrates
7. Denitrification