Topic 4 Bioenergetics Flashcards
What is Photosynthesis
- The process of plants producing their own food.
- The food it produces is Glucose
- Photosynthesis uses energy to change Carbon dioxide and water into Oxygen and Glucose
- Glucose is the used for making cell walls and proteins
Which gas is used in photosynthesis
Carbon dioxide
Which gas is produced by photosynthesis
Oxygen
Name the part of the Plant cell that contains chlorophyll
Chloroplasts
What role does chlorophyll play in photosynthesis
Chlorophyll is the green pigment found in chloroplasts and its role is to absorb light
- Energy is transferred to the chloroplasts from the environment by light making photosynthesis Endothermic
what is the word equation for photosynthesis
Carbon Dioxide + water - light/chlorophyll - Glucose + Oxygen
Write down the symbol equation for photosynthesis
6CO2 + 6H2O - light - C6 H12 O6 +6O2
What chemical substance has the symbol C6 H12 O6
glucose
3 identical plants were grown for a week.
Table shows the number of hours of sunlight exposure each plant received A =3, B=7, C= 10
Which plant produced the most glucose and why
Plant C as it received the most exposure to the sunlight so it was able to photosynthesis for a longer period of time. The Process of Photosynthesis produces glucose. The more photosynthesis the more glucose will have been produced
Table below shows the average number of chloroplasts found in 3 different type of plant cells.
1 = 20, 2 = 0, 3 = 51
Which plant has the highest rate of photosynthesis
Plant 3 as it has the highest average number of chloroplasts per cell. Chloroplasts contain chlorophyll which absorbs sunlight an essential element of Photosynthesis
By which process do plants breakdown glucose in order to transfer energy to their cells
Respiration - is a process where energy is released from the breakdown of glucose. This energy can then be used to convert the rest of the glucose into various different substances which they can use to build new cells and grow (cellulose)
What do plants use cellulose for
- Glucose is converted into cellulose which is used to create cell walls especially in rapid growing plants.
- These cell walls support and strengthen the plant cells.
What do plants absorb from the soil to make proteins with
Nitrate Ions
- Glucose combined with nitrate ions create Amino acids (the building blocks which make up proteins)
What two substances can glucose be converted into for storage in plants
Lipids (Fats/Oils) - Plants store lipids in seeds e.g.sunflower seeds
Starch - glucose is stored as starch so it is ready for use when photosynthesis isn’t happening e.g.in the winter when sunlight is less. Starch is stored in roots, stems, seeds and leaves
Why is starch better for storage than glucose
Starch is insoluble so it doesn’t draw up water and cause the cells to swell
What is meant by the term limiting factor of photosynthesis
Anything that stops photosynthesis from happening any faster e.g. in winter Light intensity would be the limiting factor due to the lack of sunlight lowering the rate of photosynthesis
Give three environmental conditions which can affect the rate of photosynthesis
Light Intensity - Light provides energy needed for photosynthesis therefore lack of light slows the rate of photosynthesis
Carbon dioxide concentration - The volume of CO2 in the air can sometimes affect the rate of photosynthesis. A plant cant synthesise if there is insufficient CO2 in the air.
Temprature - At low temperatures, the rate of photosynthesis is limited by the number of molecular collisions between enzymes and substrates. At high temperatures, enzymes are denatured
What is used to investigate the rate of photosynthesis
- Using an aquatic plant such as canadian pondweed.
- The faster the rate at which the plant produces oxygen the faster the rate of photosynthesis will be
How do you investigate the rate of photosynthesis
- Place a white light at a specific distance away from teh pond weed and leave for 2min for the plant to adjust to the light
- The pond weed is left to photosynthesise for a set amount of time
- Oxygen released by the plant will collect in a capillary tube
- At the end of the time a syringe is used to draw the gas bubble up the tube and a ruler is used to measure the length of the bubble (This is proportional to the volume of O2 produced
- Repeat twice and take the mean volume of O2
- Then repeat the whole experiment with the light source at a different distance
In the rate of photosynthesis experiment what is the dependant variable
Dependant variable is the length of the gas bubble
The dependant variable refers to what it is your measuring or the outcome of the experiment
In the rate of photosynthesis experiment what is the independant variable
The independent variable will be the light intensity
The independent variable is the variable which you change in an experiment
How do you calculate the ate of photosynthesis
Divide the total length of the bubble by the time taken to produce it e.g.
- After 5min a gas bubble measuring the length of 25mm was taken
Firstly convert 25mm into cm
25/10 = 2.5cm
- Then divide the length by the time taken
Rate = 2.5cm /5min = 0.5cm/min
Why do farmers use artificial environments in order to grow plants
It allows them to create an ideal environment for plant growth. Maximise the rate of photosynthesis which in turn maximises the rate of plant growth
What conditions can be controlled using a greenhouse
Light - using artificial light after the sun goes down to maximise their potential photosynthesis time
Carbon dioxide - Paraffin heaters can be used to heat the green house. As the paraffin burns Carbon Dioxide is produced as a by product
Temperature - Greenhouses help trap the suns heat in turn making sure that temperature doesn’t become a limiting factor for photosynthesis
What is respiration
Respiration is the process of transferring energy from the breakdown glucose which goes on in every cell.
Respiration is Exothermic meaning it releases heat /transfers energy to the environment e.g. breathing out warm air
What is aerobic respiration
Aerobic respiration is respiration which uses oxygen and is the most efficient way to transfer energy from glucose
What do organisms use energy from respiration for
Organisms use energy from respiration to build up larger molecules from smaller ones (like proteins from amino acids)
What do Animals use energy from respiration for
Animals including humans use energy from respiration to allow their muscles to contract allowing them to move
What do Mammals and Birds use energy from respiration for
Mammals and Birds use energy from respiration to maintain their body temperature keeping their temperature at a constant
What is anaerobic respiration
Anaerobic respiration is the process of producing cellular energy from glucose without oxygen.
When does the body use anaerobic respiration
The body uses anaerobic respiration during exercise or increased physical activity when the body cant get enough oxygen to the muscles
What is produced by anaerobic respiration
Lactic acid is a by product of anaerobic respiration. Anaerobic respiration is the incomplete breakdown of glucose making lactic acid.
What is the word equation for anaerobic respiration in muscle cells
Glucose - Lactic acid
What is oxygen debt
Oxygen debt is the amount of extra oxygen the body needs after exercise in order to react with the lactic acid and remove it from the cells.
How does the liver help get rid of lactic acid in the muscles
The blood that enters your muscles transports the lactic acid to the liver where it is oxidised and broken down back into glucose.
What is the word equation for anaerobic respiration in plants and yeast cells
Glucose - Ethanol + Carbon dioxide
What is anaerobic respiration also known as in yeast cells
Fermentation - In the beer industry the fermentation process produces alcohol.
In the bread making industry the fermentation process is what makes the bread rise
Compare anaerobic and aerobic respiration
Aerobic:
- Oxygen needed
- C02 and water are made
- Produces large amounts of energy
Anaerobic Respiration:
- Does not require oxygen
- Produces Lactic Acid (in humans)
- Ethanol (in Plants and yeast)
- Produces small amount of energy
How is lactic acid formed
Lactic acid is formed from the incomplete oxidation of glucose during anaerobic respiration (Energy is transferred from glucose to cells without using oxygen)
What do muscle cells use oxygen for during exercise
Oxygen is used to transfer energy from glucose which is then use to contract the muscles
The body has what three responses to increased respiration in cells when exercising
- Increase in breath rate and breath Volume to meet the demand for extra oxygen
- Increase in heart rate in order to make your blood flow more quickly delivering more oxygen and glucose to the cells for respiration and taking more carbon dioxide away.
What are the two reactions from the body after vigorous exercise.
- The body cant supply oxygen to the muscles quickly enough so they start respiring anaerobically.
- Lactic Acid build up due to the transfer of energy from glucose without the presence of oxygen
- Muscle fatigue where muscles get tired and stop contracting efficiently
What is meant by the term metabolism
The sum of all chemical reactions in a cell or the body
What is glucose used/converted into in plant cells
Cellulose = to strengthen plant cell walls
Starch = This is a storage form of Glucose e.g. potatoes
Glucose also reacts with nitrate ions to make amino acids which are then used to synthesise proteins
What is glucose used/converted into in Humans and other Animals
Glycogen = converted into glycogen which is a storage form of glucose
What are Lipid molecules made from
1 molecule of glycerol and 3 molecules of fatty acids
What is formed when glucose combines with nitrates
Amino acids
What component of urine is produced from the breakdown of excess protein
Urea
Where in a plant cell does photosynthesis take place
chloroplasts
Tim wants to measure the effect of light intensity on the rate of photosynthesis. He follows an experiment from a science mag where discs cut from leafs are put into a solution 0.2% concentrated (which serves as a carbon dioxide source) and put into a syringe under a light source. He then timed how long it took for the discs to float to the top. Results below:
Light Intensity A = 18 min for discs to float to top
Light Intensity B = 9 min
Light Intensity C = 11 min
Which Light intensity do you think was the highest, explain why
B because the discs floated to the top in a shorter time than the other Light intensities. This would indicate that more photosynthesis is taking place causing the cells to produce oxygen filling the air spaces in the leaf and causing them to float.
Tim thinks that in an experiment measuring the effect of light intensity on the rate of photosynthesis, if he keeps increasing the light intensity the rate of photosynthesis will continue to increase.
Is he right? explain your answer.
- Increasing the light intensity will increase the rate of photosynthesis up to a point but once this point is reached the increase in light intensity will have no effect on the rate.
- Other limiting factors will need to be considered in order to increase the rate such as carbon dioxide concentration or temperature increase
Tim wants to measure the effect of light intensity on the rate of photosynthesis. He follows an experiment from a science mag where discs cut from leafs are put into a solution 0.2% concentrated (which serves as a carbon dioxide source) and put into a syringe under a light source. He then timed how long it took for the discs to float to the top. Results below:
Light Intensity A = 18 min for discs to float to top
Light Intensity B = 9 min
Light Intensity C = 11 min
Tim conducts the experiment again using light intesity A but increases the solution (which serves as a carbon dioxide source) from a concentration of 0.2% to 0.8%
Do you think it will take less than 18 min for the discs to float? Explain why.
Yes because the increased carbon dioxide concentration will increase the rate of photosynthesis causing the discs to float to the top in a faster time
Photosynthesis produces glucose explain fully how this glucose can be used
used for respiration
converted to cellulose to strengthen cell walls
converted to starch for storage
converted to lipids for storage
combined with nitrates to form amino acids which can be joined to form proteins
