Download Describe how cells are used in the production of

Describe how cells are used in the production of yoghurt and
alternative fuel.
Include in your answer for both, the type of cell used, the
substrate and the products.
ANSWER:
Answers may include:
• (Both processes involve) anaerobic
respiration/fermentation.
(Maximum of three from)
• (Yoghurt cell type) bacteria
• (Yoghurt substrate) lactose/sugar in milk
• (Yoghurt product) lactic acid
(Maximum of three from)
• (biogas cell type) bacteria
• (biogas substrate) organic waste
• (biogas product) methane
• (gasohol cell type) yeast
• (gasohol substrate) sugar(cane)/glucose
• (gasohol product) ethanol/alcohol
• (Gasohol) ethanol/alcohol + petrol = fuel/gasohol
1
Describe the function of yeast in bread making and the
anaerobic pathway of respiration involved in this process.
ANSWER:
(Maximum of 2 from)
• Yeast contain enzymes (for anaerobic respiration)
• Yeast ferment sugar/glucose
• Carbon dioxide produced
• (CO2) makes the
• dough/bread rise
(Maximum of 3 from)
• In the absence of oxygen
• (first stage) glycolysis occurs
• Glucose converted into pyruvic acid(s)
• Pyruvic acid is broken down
• To ethanol/alcohol and carbon dioxide
• Anaerobic conversion is irreversible
• (glycolysis/glucose breakdown) produces 2 ATP
• Enzymes used for anaerobic respiration
2
The diagram below shows a container used for home wine
production.
Describe the anaerobic pathway of respiration which results
in wine production in this container.
ANSWER:
• The yeast provides the enzymes for the process.
• The grape juice contains the sugar/glucose.
• The first stage of anaerobic respiration is called glycolysis.
• In this stage the sugar/glucose is broken down into pyruvic
acid.
• 2 ATP molecules are produced per glucose molecule.
• The second stage is a fermentation process.
• They pyruvic acid is broken down in the absence of oxygen.
• Carbon dioxide gas is given off.
• Alcohol is also produced.
• The is an irreversible reaction.
3
The diagram below shows the appearance of human red blood cells in an
isotonic solution.
Describe and explain the events which would take place if these red blood
cells were transferred to pure water.
ANSWER:
DESCRIBE
2 points from:
• Water moves/diffuses into cells.
• The cells swell/fill up with water.
• The cell membrane splits/the cell bursts/haemolyses.
EXPLAIN
2 points from:
• The water is hypotonic to the cell contents/the cell contents are
hypertonic/the surrounding water has a higher concentration of water than
the cell contents/the cell contents have a lower water concentration than
the surrounding water.
• Water moves from a high concentration outside the cell to a lower
concentration into the cell.
• Water moves by osmosis.
4
The diagram below represents an experiment set up as
shown then left for 1 hour.
Name and describe the two processes by which molecules
would have moved.
ANSWER:
Process 1
(maximum of 3 marks)
• Diffusion
• Movements of substance/molecules/glucose from high to low concentration or movement
of a substance/molecules/glucose down a concentration gradient.
• Glucose will move out (of tubing bag)
• Starch will not move (out)
• Glucose molecules small/starch molecules large
• Membrane controls entry/exit
Process 2
(maximum of 3 marks)
• Osmosis
• Movement/diffusion of water from high to low concentration or movement/diffusion of
water down a concentration gradient.
• Through a selectively membrane.
• Water will move in (through the membrane)
• Water is hypotonic to mixture or mixture is hypertonic to water
5
The diagrams below show animal and plant cells in isotonic
solutions
Describe the osmotic effect of transferring
a) The animal cell into a hypotonic solution (water).
b) The plant cells into a hypertonic solution (strong salt).
ANSWER:
(maximum of 3 marks)
• Surrounding/hypotonic solution has higher water concentration.
• Water enters/fills (animal) cells/water diffuses into cells.
• By osmosis/from HWC to LWC
• Cells swells
• And bursts
• Because no cell wall present.
(maximum of 3 marks)
• Surrounding/Hypertonic solution has lower water concentration
• Water leaves (plant) cells/water diffuses out of cells
• By osmosis/from HWC to LWC (if not already marked)
• Vacuole shrinks
• Cell membrane pulled away from cell wall/cell contents shrink
• Cell becomes plasmolysed/flaccid.
6
Describe the properties of enzymes and the function of
enzyme phosphorylase in a synthesis reaction
ANSWER:
(maximum of 3 from)
• (enzymes are) composed of proteins
• (enzymes aree) catalysts/speed up reactions/lower
activation energy required for a reaction to take place.
• (enzymes) can be reused/(enzymes) are unchanged in the
reaction
• They have an active site
• Specific substrate fits into enzyme/enzyme substrate
complex/lock and key/complementary/suitable labelled
diagram/enzymes are specific or example
• Any correct point about temperature/pH/affecting enzyme
activity/structure
(maximum of 2 from)
• Glucose-1-phosphate/G-1-P is the substrate
• Starch is the product/is made
• Small/simple molecules to large/complex molecules
7
The diagram below represents an amylase molecule
Describe and explain the events that take place when the
enzyme is added to a starch suspension.
ANSWER:
DESCRIBE
(maximum of three)
• Starch (molecules) attach to the enzyme (molecules).
• Starch is broken down/a reaction takes place.
• Maltose/glucose/sugar is formed.
EXPLAIN
(maximum of three)
• The enzyme has a specific shape/amylase is specific to
starch/amylase only reacts with starch.
• The active site is the place on the enzyme where the
starch fits/description of active site.
• Bonds are broken between molecules.
8
Give an account of the properties of enzymes.
ANSWER:
• Enzymes are catalysts/speed up/change or control the rate
of reactions.
• Enzymes lower the energy required for a reaction to take
place.
• Enzymes are unchanged by reactions.
• Enzyme molecules are used over and over again.
• Enzymes are involved in reactions which break down and
build up molecules.
• Enzymes have a characteristic shape.
• Enzymes contain an active site.
• Enzymes can form an enzyme substrate complex/substrate
fits into enzyme active site.
• Enzymes are specific or description of named example.
• Enzymes are affected by temperature/have an optimum
temperature.
• Enzymes are affected by pH/have an optimum pH.
• Enzymes are denatured at high temperatures.
• Enzymes are composed of proteins/amino acids.
9
The diagram below represents an animal cell that is
respiring aerobically.
Describe the two stages of aerobic respiration. Include the
names of the raw materials and the products of the two
stages.
ANSWER:
(maximum of three)
• Enzyme controlled
• Glucose (raw material)
• Converted to pyruvic acid
• Glycolysis
• Is anaerobic/oxygen not used
• Energy is released
• 2 APT produced (per glucose molecule)
(maximum of three)
• Enzyme controlled reaction (only if not already awarded the mark)
• Energy released (only if not already awarded the mark)
• Pyruvic acid
• Broken down to carbon dioxide and water
• Oxygen required/aerobic
• 36 ATP produced/total 38 ATP produced (per glucose molecule)
10
Describe the stages in aerobic respiration.
ANSWER:
(maximum of two)
• Respiration is the process by which cells
obtain/release/give out energy.
• Respiration involves a series of enzyme-controlled
reactions.
• Aerobic respiration requires oxygen/takes place when
oxygen is available.
(maximum of two)
• In the first stage glucose is broken down into pyruvic acid.
• First stage is called glycolysis.
• 2 molecules of ATP formed in the first stage.
• Oxygen in not required for this stage.
(maximum of two)
• In this second stage pyruvic acid is broken down into
carbon dioxide and water.
• Second stage can only happen in the presence of oxygen.
• 36 molecules of ATP are formed in the second stage.
(maximum of two)
• 38 mols of ATP are produced in total from each molecule of
glucose.
• ATP is produced from ADP and Pi.
• Energy is stored as/in molecules of ATP.
11
The flow diagram below shows the two stages of
photosynthesis.
Name and describe Stage 1 and Stage
ANSWER:
Stage 1 – photolysis
• This stage occurs in the chloroplasts in the presence of
light/Chlorophyll is used to absorb light energy.
• Water is split to produce hydrogen and oxygen.
• The hydrogen combines with a hydrogen acceptor.
• The oxygen is given off as a by-product.
•
•
•
•
Stage 2 – Carbon Fixation
The hydrogen from photolysis combines with CO2.
This requires the ATP produced during photolysis.
Glucose is produced.
This stage is controlled by enzymes.
12
The rate of photosynthesis is limited by certain
environmental factors.
Name two limiting factors and describe how the growth of
greenhouse plants in winter can be increased.
ANSWER:
(Maximum of 2 from)
• Carbon dioxide (concentration)
• Light (intensity)
• Temperature
(Maximum of 3 from)
• Changing these factors to an optimum level (for
photosynthesis)
• By artificial lighting or additional heating or adding carbon
dioxide.
• (Rate of) photosynthesis is increased
• More glucose or food is available (for growth)
13
The diagrams below show the two stages of photosynthesis.
Describe what happens during the two stages:
a) Photolysis
and
b) Carbon fixation
ANSWER:
(Maximum of 3 from)
• Chlorophyll/chloroplasts absorb (energy of) light.
• To split water into hydrogen and oxygen.
• Oxygen released.
• ATP produced.
• Light energy converted to chemical energy.
• Hydrogen combines with a hydrogen acceptor.
•
•
•
•
•
(Maximum of 3 from)
Carbon dioxide enters.
This stage is enzyme controlled.
APT supplies the energy needed.
Hydrogen joins with carbon dioxide.
Glucose/starch/cellulose is formed.
14