B4 - Bioenergetics Flashcards
(34 cards)
Describe the features of a greenhouse which help provide an ideal environment for plant growth
Enclosed to prevent pests and diseases from providing environmental stress on the plants
Provided with a supply of artificial light to prevent light from becoming a limiting factor
Use fertilisers containing magnesium
Contain paraffin heaters to increase levels of carbon dioxide to prevent carbon dioxide being a limiting factor and provide heat
Explain why the body changes its breathing and heart rates during and after exercise
During exercise, there is an increase in demand for energy so the muscles can contract more. This means that the breathing rate, heart rate and breadth volume increases to supply muscles with more oxygenated blood and glucose. This results in more aerobic respiration so there is a greater rate of energy release for muscle contraction so the body can exercise for longer as this prevents cramps and fatigue
If insufficient oxygen is supplied, anaerobic respiration occurs and the incomplete oxidation of glucose causes a build up of lactic acid which creates an oxygen debt. This means the breathing rate after exercise remains high before the blood transports the lactic acid back to the liver where it is converted to glucose
Describe the process of photosynthesis
Light energy is absorbed by chlorophyll in chloroplasts in some plants/algal cells. This energy is used to convert carbon dioxide and water into glucose and oxygen
What type of reaction is photosynthesis?
Photosynthesis is endothermic, because energy is transferred from the environment into the chloroplast by light
ENdothermic = energy ENtering
EXothermic = energy EXiting
What is the word and symbol equation for photosynthesis?
6C02 + 6H20 —> C6H1206 + 602
Carbon dioxide + water —> glucose + oxygen
What is a limiting factor (of photosynthesis)?
Factors that restrict the rate of photosynthesis if in low levels
How does temperature affect the rate of photosynthesis?
As temperature increases, the rate of photosynthesis increases so temperature is the limiting factor as photosynthesis is controlled by enzymes, which gain kinetic energy as they reach optimum temperature
Above an optimum temperature, the rate of photosynthesis decreases as the enzymes denature because the active site changes shape
How does light intensity affect the rate of photosynthesis?
As light intensity increases, the rate of photosynthesis increases so light intensity is the limiting factor as light provides energy needed for the reaction
After a certain point, the rate of photosynthesis stops increasing because another factor is limiting such as temperature or CO2 concentration
How does carbon dioxide concentration affect the rate of photosynthesis?
As carbon dioxide increases, the rate of photosynthesis increases so it is the limiting factor because CO2 is one of the raw materials needed for photosynthesis
After a certain point, the rate of photosynthesis stops increasing because another factor is limiting, such as temperature or light intensity
How does the concentration of chlorophyll affect photosynthesis?
Some plants are affected by disease, such as TMV, and environmental stress, such as magnesium deficiency. Variegated leaves have reduced chlorophyll in white areas
This affects how much light energy can be absorbed for photosynthesis
What is the inverse square law?
Light intensity is inversely proportional to 1/distance²
How can a gardener maximise photosynthesis?
Remove limiting factors -> gain maximum rate of photosynthesis -> increase plant yield
Profit from extra yield must be greater than the costs of providing conditions
What are the control variables in RP6?
Temperature
C02 supply
Length/type of aquatic organism
Colour of light
How can you investigate the effect of light intensity on the rate of photosynthesis?
Fill a boiling tube with sodium hydrogen carbonate solution and place it 10 cm away from an LED light source
Place a piece of pondweed into the boiling tube with a horizontally cut end at the top
Leave the tube for five minutes for the pondweed to acclimatise
Start a stopwatch and record the number of bubbles produced in one minute
Repeat the experiment 3 times at five different distances and calculate a mean
At a greater light intensity, more bubbles are produced, as light is needed for photosynthesis
Plot a graph of distance against number of bubbles produced
In RP6, Why is the aquatic organism placed in a solution of sodium hydrogen carbonate solution?
In RP6, How could you test the bubbles to show they contained oxygen?
Why is counting bubbles Not an accurate way of measuring the volume of oxygen produced?
How could the method be improved to measure the rate of photosynthesis more accurately?
What is the advantage of using an LED light source?
To provide carbon dioxide so that it is not a limiting factor
Add a burning splint, it will buy more brightly
The bubbles are different sizes, and some bubbles can be easy to miss
Measure the volume of oxygen released in a gas syringe and increase the length of time
Does not omit a lot of infrared radiation so temperature is controlled. This is important because temperature affects the rate as photosynthesis is controlled by enzymes
How could RP6 be modified to investigate the effect of wavelength of light on the rate of photosynthesis?
Place different coloured filters over the bulb
How could RP6 be modified to investigate the effect of CO2 and temperature on the rate of photosynthesis?
Use different concentrations of sodium hydrogen carbonate solution
Use different temperature water baths
What are the uses of glucose from photosynthesis? (SCARFo)
Used for respiration to release energy
Converted into starch for storage that can be converted back to glucose when photosynthesis is not occurring. Unlike glucose, It is insoluble so will not affect the movement of water in and out of cells by osmosis
Used to produce fat or oil for energy storage
Used to produce cellulose, which strengthens the plant cell wall
Used to produce amino acids/proteins. Glucose is combined with nitrate ions, absorbed from soil to form amino acids which are used in protein synthesis
Describe cellular respiration
A series of chemical reactions that release energy from glucose
Occur continuously in all living cells and is an example of an exothermic reaction
What are the uses of energy released in respiration?
In chemical reactions to build larger molecules
To keep warm
For movement, such as muscle contraction in animals or transport of substances in the phloem of plants
What is the word and symbol equation for aerobic respiration?
C6H1206 + 602 —> 6CO2 + 6H20
Glucose + oxygen —> carbon dioxide + water
What is the word equation for anaerobic respiration in muscles?
Glucose —> lactic acid
What is the word equation for anaerobic respiration in plant and yeast cells?
Glucose —> ethanol + carbon dioxide
Compare aerobic and anaerobic respiration
Aerobic respiration uses oxygen, whereas anaerobic respiration does not
In aerobic respiration, the oxidation of glucose is complete, Whereas it is incomplete in anaerobic respiration
In anaerobic respiration, the relative amount of energy transferred is high, Whereas it is low in Anaerobic respiration
Aerobic respiration forms carbon dioxide and water, whereas in anaerobic respiration in animal cells, it forms lactic acid and in plant cells and yeast cells, it forms ethanol and carbon dioxide
