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Flashcards in B4 Deck (34)
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1
Q

What is photosynthesis?

A
  • a chemical reaction which takes place in plants where glucose is made using energy from the sun
2
Q

Where in the plant does it take place?

A
  • in chlorophyll (a chemical found in chloroplasts)
3
Q

What type of reaction is photosynthesis?

A
  • endothermic
4
Q

Write the word equation for photosynthesis

A
  • carbon dioxide + water → glucose + oxygen
5
Q

Write the chemical symbols for the reactants of photosynthesis

A
  • CO2 = carbon dioxide and H2O = water
6
Q

Write the chemical symbols for the products of photosynthesis

A
  • C6 H12 O6 = glucose and O2 = oxygen
7
Q

What are the uses of the glucose which the plant makes in photosynthesis

A
  • for respiration
  • stored as fats or oils
  • to make cell walls
  • to make amino acids
  • to store as insoluble starch granules
8
Q

What are the 4 main limiting factors affecting the rate of photosynthesis?

A
  • the light intensity
  • the concentration of CO2
  • the temperature
  • the amount of chlorophyll a plant has
9
Q

What is a limiting factor?

A
  • is something which can stop photosynthesis happening any faster
10
Q

Explain the graph when light intensity is the limiting factor

A
  • at first, as you increase the light intensity , the rate of photosynthesis increases . Light is the limiting factor
  • at a certain point, the graph goes flat and no matter how bright the light is, photosynthesis will not go any faster
  • this is because light intensity is no longer the limiting factor. The concentration of CO2 or the temperature is now the limiting factor
11
Q

Explain the graph when CO2 concentration is the limiting factor

A
  • at first, as you increase the CO2 concentration, the rate of photosynthesis increases. CO2 concentration is the limiting factor
  • at a certain point, the graph goes flat and no matter how much CO2 there is, photosynthesis will not go any faster
  • this is because concentration of CO2 is no longer the limiting factor. The light intensity or the temperature is now the limiting factor
12
Q

Explain the graph when temperature is the limiting factor

A
  • at first, as you increase the temperature, the rate of photosynthesis increases. Temperature is the limiting factor
  • the enzymes needed for photosynthesis work best at the temperature shown by the peak of the graph
  • after this point, the rate of photosynthesis will slow down as the temperature is too high and the enzymes will start to denature
13
Q

What is respiration?

A
  • a chemical reaction which releases energy from glucose in all cells
14
Q

What type of reaction is respiration?

A
  • exothermic
15
Q

Where does respiration take place?

A
  • in the mitochondria of cells
16
Q

Give 3 ways the organisms use the energy transferred by respiration

A
  • to build large molecules from smaller ones
  • to move
  • to keep warm
17
Q

What is metabolism?

A
  • the total of all the reactions taking place in a cell or body
18
Q

What controls the rate of chemical reactions in the body?

A
  • enzymes
19
Q

Give examples of 5 large molecules which are made in the body (say what each is made from)

A
  • starch = made from glucose
  • glycogen = made from glucose
  • cellulose = made from glucose
  • lipids (fats) = made from glycerol and 3 fatty acids
  • proteins = made from amino acids
20
Q

Give 2 examples of reactions in the body where large molecules are broken down into smaller ones

A
  • respiration = the breakdown of glucose

- excess protein = broken down to make urea

21
Q

What are the 3 type of respiration?

A
  • aerobic respiration
  • anaerobic respiration in muscle cells
  • anaerobic respiration in plant and yeast cells
22
Q

When does anaerobic respiration take place in muscle cells?

A
  • when not enough oxygen is available
23
Q

What is the word equation for anaerobic respiration in muscle cells?

A
  • glucose → lactic acid
24
Q

Compare the amount of energy released by this type of respiration with aerobic respiration

A
  • much less energy is released in anaerobic respiration
25
Q

Write the word equation for anaerobic respiration in plants and yeast cells

A
  • glucose → ethanol + carbon dioxide
26
Q

What is another name for anaerobic respiration in yeast cells?

A
  • fermentation
27
Q

How do we use this type of respiration in the food and drink industry (2 ways)

A
  • baking bread = the carbon dioxide bubbles make bread rise

- making beer/wine = the fermentation makes ethanol which is the alcohol in the drinks

28
Q

Compare aerobic , anaerobic in muscle cells(mc) and anaerobic in plants & yeast respiration(p&y)

A

ALL THREE:

  • use glucose
  • release energy
  • happen in mitochondria

AEROBIC AND ANAEROBIC IN P&Y RESPIRATION BOTH:

  • produce CO2

ANAEROBIC IN MC AND ANAEROBIC IN P&Y RESPIRATION BOTH:

  • no oxygen
  • small amount of energy

however aerobic respiration also:

  • produces water
  • needs oxygen

whereas anaerobic in mc respiration also:

  • produces lactic acid

also anaerobic in p&y respiration:

  • produces ethanol
29
Q

Explain how we respond to exercise (1 way)

A
  • When we exercise we need more energy so muscles can contract more
  • We need to do more respiration so our breathing rate increase and we take deeper breaths to get more oxygen into our body
  • Our heart rate increase to pump more oxygenated blood to our muscle cells
30
Q

Explain how we respond to exercise (2 way)

A
  • unfortunately, we cannot always get enough oxygen to our muscles
  • this means our muscles respire anaerobically
  • this releases less energy than aerobic respiration
  • another problem is that lactic acid builds up in muscles, which can cause muscle fatigue
  • this stops muscles from contracting efficiently
  • after you stop exercising you have an oxygen debt
31
Q

What is the definition of oxygen debt?

A
  • oxygen debt is the amount of extra oxygen the body needs after exercise to react with the build up of lactic acid and remove it from the cells
32
Q

Describe the process by which lactic acid gets fully broken down

A
  • the lactic acid reacts with oxygen and forms carbon dioxide and water
33
Q

Use ideas about oxygen debt to explain why we continue to breathe heavily, even after stopping exercise

A
  • we need to get more oxygen into the blood
34
Q

How is the blood involved in removing lactic acid which has built up in the muscles?

A
  • the blood transports the lactic acid to the liver, where it is converted back to glucose