B4- Bioenergetics Flashcards
Where does photosynthesis take place in the plant cells?
Chloroplasts
Is photosynthesis endothermic or exothermic?
Endothermic
What is the SYMBOL equation for photosynthesis
6C02 +6H2O➜C6H12O6+6O2
What are the five ways plants use glucose?
- For respiration
- Making cellulose
- Making amino acids
- Stored as fats or oils
- Stored as starch
What 3 things affect the rate of photosynthesis?
- Light
- Concentration of CO2
- Temperature
Can chlorophyll be a limiting factor of photosynthesis and how?
Yes, the amount of chlorophyll in a plant can be affected by disease or environmental stress, such as a lack of nutrients. These factors can cause chloroplasts to become damaged or to not make enough chlorophyll. This means the rate of photosynthesis is reduced because they can’t absorb as much sunlight
Describe how light impacts the rate of photosynthesis?
As the light level is raised, the rate of photosynthesis increases steadily- but only to a certain point
Describe and explain how light impacts the rate of photosynthesis?
As the light level is raised, the rate of photosynthesis increases steadily- but only to a certain point. Beyond that, it won’t make a difference- as light intensity increases, the rate will no longer increase. this is because it’ll be either the temperature or the CO2 level which is now the limiting factor, not light
What temperature is too hot for enzymes?
45°C, it is rare for outdoors but can get to that in a greenhouse
How do greenhouses work?
They help trap the Sun’s heat, and make sure that the temperature doesn’t become a limiting factor
What is a disadvantage of a greenhouse?
Expensive
Define respiration.
The process of transferring energy from glucose, which goes on in every cell
Do all living things respire?
Yes
Is respiration endothermic or exothermic?
Exothermic
What are three examples of how organisms use the energy transferred from respiration?
- To build up larger molecules( e.g proteins or amino acids)
- In animals it helps the muscles to contract
- In mammals and birds the energy is used to keep their body temperature steady
What are chemical reactions controlled by in cells?
Enzymes
Is starch a big molecule?
Yes
What is starch made from?
Small glucose molecules
What are lipid molecules made from?
1 molecule of glycerol and three fatty acids,which are made into proteins
When is glucose broken down?
Respiration
What is urea made from?
Broken down proteins
Define metabolism
The sum of all the reactions that happen in a cell or the body is called metabolism
Aerobic respiration doesn’t need much oxygen.TRUE/FALSE
False, it needs plenty of oxygen
Where does most of the reaction in aerobic respiration?
Mitochondria
What is the symbol equation for aerobic respiration?
C6H1206+6O2 ⇢6C02+6H2O
When is anaerobic respiration used?
When there isn’t enough oxygen
What’s the word equation for anaerobic respiration fro animals?
Glucose ⇢ Lactic acid
What’s the word equation for anaerobic respiration in plants and yeast?
Glucose ⇢ Ethanol Carbon Dioxide
What is anaerobic respiration called in yeast?
Fermentation
What is oxygen debt?
The amount of oxygen your body needs to react with the buildup of lactic acid and remove it form the cell
What is the name of a section of a chromosome that controls a characteristic?
gene(s)
Cell E in Figure 2 contains 8 chromosomes. box
Cell E divides by mitosis.
How many chromosomes will each new cell contain?
8
Protease is an enzyme.
Protease breaks down protein.
What is protein broken down into
amino acids
Why is protein needed by the body
any one from:
• for growth
• for repair / replacement (of
cells / tissues / organs)
Which organ in the human digestive system produces protease
stomach
Describe how you would test a sample of food to show it contains protein. box
Give the reason for any safety precautions you would take.
- grinding up the food
- add Biuret reagent (allow CuSO4 and NaOH) to food (sample)
- protein turns solution (from blue) to purple / lilac
- wear goggles to protect eyes
- clean up spills immediately
- Biuret / NaOH is an irritant / corrosive / poisonous
What is the platelet’s function
Helps the blood to clot
Suggest why blood flow through the coronary arteries is lower in people with
coronary heart disease
(because coronary) arteries /
they are narrower
Earthworms have a large surface area to volume ratio.
Suggest why a large surface area to volume ratio is an advantage to an earthworm.
(earthworm) can absorb more
oxygen (in a given time)
or
increases / more gas exchange
What is photosynthesis
The process by which plants synthesise
glucose using light energy from the Sun.
Light energy is converted into chemical
energy.
Where does photosynthesis take place?
Within chloroplasts in leaf palisade
cells. They contain chlorophyll, a pigment
which absorbs light energy.
State the equations for photosynthesis (word and symbol)
Word: carbon dioxide + water → glucose + oxygen
Symbol: 6CO2
+ 6H2O → C6H12O6+ 6O2
Is photosynthesis an endothermic or
exothermic reaction, and why
Endothermic - energy is transferred from
the environment to chloroplasts by light
How can you show that a plant gives off oxygen
during photosynthesis?
Using a water plant (eg. Elodea), collect gas
bubbles produced during photosynthesis. The
gas will relight a glowing splint as it contains
oxygen.
Give examples of leaf adaptations which
maximise the rate of photosynthesis
● Broad leaves - maximise surface area.
● Thin leaves - short diffusion distance.
● Chlorophyll present - trap light energy.
● Veins - transport water to leaves via xylem, remove photosynthesis
products via phloem.
● Air spaces - allow CO2 to enter and O2 to leave.
● Guard cells - control opening of stomata for gaseous exchange and
prevent water loss.
What are the four main factors that affect the rate
of photosynthesis
● Temperature
● Light intensity
● Carbon dioxide concentration
● Amount of chlorophyll
How does temperature affect the rate of
photosynthesis?
Increasing the temperature increases the rate of
photosynthesis as the kinetic energy of particles
is increased. The rate decreases past a certain
temperature as enzymes become denatured
How does light intensity affect the rate of
photosynthesis?
Increasing the light intensity increases the
rate of photosynthesis until another factor
becomes limiting
How does carbon dioxide concentration affect
the rate of photosynthesis
Increasing the carbon dioxide concentration
increases the rate of photosynthesis (until
another factor becomes limiting) as CO2
is required to make glucose.
How does the amount of chlorophyll affect the
rate of photosynthesis?
Decreasing the amount of chlorophyll (eg. due to
a lack of magnesium) decreases the rate of
photosynthesis as chlorophyll is required to
absorb light energy
What is a limiting factor
An environmental factor which can
restrict the rate of photosynthesis eg.
light intensity
Explain how you can calculate the rate of
photosynthesis by measuring oxygen production
● Set up bubble potometer apparatus (pondweed in a
sealed tube of water, attached to a capillary tube and a gas syringe).
● Oxygen gas produced causes the bubble in the capillary
tube to move. The distance moved by the bubble is used to calculate the volume of oxygen produced
How can farmers use their knowledge of
limiting factors to increase their profits?
They can control temperature, light intensity
and CO2
concentration to achieve the fastest
possible rate of photosynthesis, leading to a
greater yield
State the law which describes the relationship
between the distance of a light source from a plant
and light intensity
Inverse square law - light intensity∝1 /
distance2
State 5 uses of the glucose produced
during photosynthesis
● Respiration ● Starch for storage ● Cellulose for strength ● Amino acid and protein synthesis (combined with nitrates) ● Lipids for energy storage in seeds
What is aerobic respiration
An exothermic reaction in which glucose
reacts with oxygen to release energy
which can be used by cells
What are the equations for aerobic respiration?
word and symbol
Glucose + oxygen → carbon dioxide + water (+energy)
C6H12O2 + 6O2 → 6CO2 + 6H2O (+energy)
Where does aerobic respiration take place
In the mitochondria
Why do organisms require the energy
released by respiration?
● Synthesis of larger molecules
● Muscle contraction
● Maintenance of body temperature
● Active transport
What is anaerobic respiration
An exothermic reaction in which glucose
is broken down to release energy in the
absence of oxygen
What is the equation for anaerobic respiration
Glucose → lactic acid (+energy)
Why is anaerobic respiration less efficient than
aerobic respiration
Glucose is not completely broken down,
so less energy is transferred.
Why can anaerobic respiration lead to muscle
fatigue
Lactic acid (product of anaerobic respiration)
builds up in muscles, preventing efficient
contraction
What is an oxygen debt
The amount of oxygen needed to convert
lactic acid into back into glucose after
anaerobic respiration
What is fermentation
A type of anaerobic respiration that
occurs in yeast cells
What is the equation for fermentation?
Glucose → ethanol + carbon dioxide (+energy)
Why is the fermentation reaction important?
It is used in the production of bread and
alcoholic drinks
What are the differences between aerobic and
anaerobic respiration
● Aerobic requires oxygen; anaerobic does not.
● Aerobic produces CO2
and water; anaerobic
produces lactic acid or ethanol + CO2.
● Aerobic transfers a greater amount of energy
How do muscles store glucose
As glycogen
What changes take place when muscular activity
increases in the body
● Heart rate increases and arteries dilate - increases
flow of oxygenated blood to muscles.
● Breathing rate increases and breathing is deeper -
increases the rate of gaseous exchange.
● Stored glycogen is converted back into glucose.
How is lactic acid transported away from the
muscles
Blood flow through the muscles transports
lactic acid to the liver, where it is oxidised
back to glucose
What is metabolism
The sum of all the reactions that take
place in a cell or an organism
How do cells use the energy transferred by
respiration
To continuously carry out enzyme-controlled
processes which lead to the synthesis of new
molecules.
Give examples of metabolic reactions
● Glucose into starch/glycogen/cellulose ● Glycerol and fatty acids into lipids ● Glucose and nitrate ions into amino acids ● Photosynthesis ● Respiration ● Breakdown of excess proteins into urea
