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GCSE B1 > 1 bioenergetics 1 > Flashcards

1 bioenergetics 1 Flashcards

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1
Q

Plants have the ability to create their own ………… using the energy from ……..

A

Food

Light

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2
Q

What species can turn light energy into chemical energy?

A

Plants
Bacteria
Algae

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3
Q

What’s the word equation for photosynthesis? And where do all the components come from

A

Carbon dioxide + water -light/chlorophyll—> glucose + oxygen

  • carbon dioxide enters the leaves through small holes (stomata) from the air
  • the leaves get water from absorbing the water from the roots
  • chlorophyll the green pigment in the chloroplast in the leaves which absorbs light
  • glucose is used in respiration to release energy or store as insoluble starch for future use
  • oxygen is released from the leaves into the air
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4
Q

What’s the equation for photosynthesis?

A

6CO_2 + 6H_2 O —light—> C_6 H_12 O_6 + 6O_2

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5
Q

Why is photosynthesis so important?

A
  • oxygen is needed for other organisms (eg animals) to carry out aerobic respiration
  • the glucose forms the basis of all food chains providing chemical energy to sustain all of the life on Earth
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6
Q

If you want to investigate if photosynthesis has happened what 4 things would you look at?

A
  • starch
  • carbon dioxide
  • oxygen
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7
Q

If your testing the starch to test for photosynthesis how would you do it?

A
  • little of the glucose created remains as glucose
  • most of it joins together to form insoluble grains of starch
  • you can use iodine solution to test for the presence of starch, which indicates photosynthesis has taken place
  • it starts as a yellow-brown liquid that turns blue-black in contact with starch
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8
Q

If your testing for photosynthesis with starch how do you know if new photosynthesis has taken place?

A
  • you have to de-starch the plant first

- you can place the whole plant dark for 24 hours, or covering a section of it with black paper

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9
Q

How do you test for starch in leaves?

A
  • testing in leaves is problematic as the waxy cuticle prevents the iodine from entering the leaf
  • the green colour also masks the colour change
  • the leaf must be prepared by boiling it in ethanol to destroy the cuticle and remover the colour
  • after rinsing in hot water to soften it up, it can be tested
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10
Q

If your testing the chlorophyll to test for photosynthesis how would you do it?

A
  • some leaves are variegated, where they have an uneven distribution of chloroplasts in the leaf cells
  • most starch is found in the green region as there is more chlorophyll to absorb light for photosynthesis
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11
Q

If your testing the carbon dioxide realised to test for photosynthesis how would you do it?

A
  • bicarbonate indicator can also be used to show photosynthesis
  • it’s very sensitive to changes in pH caused by an increase/decrease in dissolved CO2
  • CO2 is slightly acidic, so as the plant photosynthesises it removes CO2 from the solution and becomes more alkaline
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12
Q

If the bicarbonate indicator goes yellow what does it mean?

A

There’s increasing CO2

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13
Q

If the bicarbonate indicator goes red what does it mean?

A
  • red is the atmospheric CO2 level

- there’s equal respiration and photosynthesis so no charge

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14
Q

If your testing the oxygen realised to test for photosynthesis how would you do it?

A
  • we can see photosynthesis by collecting the bubbles of gas create by a plant
  • we can test the gas with s glowing splint
  • it should re-light, indicating that it’s oxygen gas
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15
Q

Explain how to investigate the rate of photosynthesis

A
  • we can measure the rate of photosynthesis by counting the number of bubbles released per minute from pond weed
  • we can change the distance of the lamp from the plant, and change the light intensity to see how that effects the rate of oxygen produced and compare it to the original rate
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16
Q

What’s the independent variable?

A

-the variable idle realty changed/selected
-X axis of a graph
(Time, distance)

17
Q

What’s the dependant variable?

A
  • the variable being measured

- y axis of a graph

18
Q

What’s the controlled variable?

A

Other factors which must be kept constant to make it fair test, so that the different experiments can be compared

19
Q

What do plants need for photosynthesis to work?

A
  • light
  • carbon dioxide
  • temperature
20
Q

Define limiting factor

A

The one value which is in the shortest supply, preventing photosynthesis from occurring faster

21
Q

What factors affect the rate of photosynthesis?

A
  • light intensity
  • carbon dioxide concentration
  • temperature
22
Q

Explain how light intensity is a limiting factor for photosynthesis

A
  • increasing the amount of light will increase the rate of photosynthesis
  • increasing the light intensity further makes no difference as another factor becomes the limiting one?
23
Q

Explain how carbon dioxide concentration is a limiting factor for photosynthesis

A
  • the atmosphere only contains 0.04% CO2 it can often be the limiting factor on a sunny day
  • increasing CO2 levels will allow photosynthesis to take place faster, until another factor becomes the limiting one
24
Q

Explain how temperature is a limiting factor for photosynthesis

A
  • photosynthesis requires enzymes for the reaction, providing more heat energy will increase the rate of the reaction
  • however, if the temperature gets too high (40-50 C) the enzymes are destroyed (denatured) and the reaction stops completely
25
Q

How and why do farmer maximise plant growth?

A
  • increasing the rate of photosynthesis improves plant growth
  • this is done by optimising the growing conditions so that the plants can grow faster, fruit earlier and give higher yields (quality of product collected)
26
Q

List the 3 ways farmers maximise plant growth

A
  • polytunnels
  • greenhouses
  • hydroponics
27
Q

Explain how polytunnels work?

A
  • plastic polytunnels cover crops in fields

- these keep plants warmer, increasing the rate of photosynthesis

28
Q

Explain how greenhouses work?

A
  • plants can also be given extra light, heat and carbon dioxide to raise the values of all the possible limiting factors (electric lights and gas-burners)
  • some greenhouses use computers to optimise each level
29
Q

Explain how hydroponics work?

A
  • plants don’t need soil, they need the nutrients in the soil
  • it’s a system where the roots of plants are in oxygenated water with a carefully controlled balance of mineral ions to optimise growth
  • one of the most important nutrients that a plant needs from soil is nitrate
  • which is necessary to build amino acids to from protein for the growth of the plant
  • farmers also add fertilisers that contain these nitrates to maximise growth
30
Q

When maximising growth of plants what do farmers need to consider?

A

They need to balance the cost of maximising each condition for plant growth with their increased profit from selling the crop

31
Q

What’s the function of glucose?

A

It’s the only organic molecule produced in photosynthesis, it forms the basis for all organic compounds within the plant

32
Q

List the 6 steps of what happens to the glucose in a plant

A
  1. CO2 and H2O go in to the plant forms glucose
  2. glucose is used to build cellulose for cell walls
  3. glucose is used in respiration fro energy
  4. glucose is used for fats and oils, which build cell membrane and store energy
  5. glucose, nitrate ions and other minerals (from the soil/ water) are converted into amino acids, to form proteins
  6. glucose is joined together to form starch for storage
33
Q

Is photosynthesis endothermic or Exothermic?

A

Endothermic, energy from the sun (the environment) is transferred to the chloroplast as light.

34
Q

In a forest woodland and plants died and grew for hundreds of years. When cleared it to grow plants it only grew for 3 years. Why? 3marks

A
  • the soil had run out of nutrients.
  • Crops absorb more nutrients then woodland
  • and the farmer never replaced the nutrients
35
Q

Some plants have variegated leaves with white parts which contain no chlorophyll. How do you think a normal leaf would compare to a variegated one? 2marks

A
  • The variegated one isn’t going to grow as fast or as well.

- variegated leaf has less surface area and less chlorophyll

36
Q

Explain how you would investigate the effect of light intensity on photosynthesis in pondweed (required practical) in 6 steps

A
  1. put a boiling tube containing hydrogen carbonate solution in a test tube rack, 10cm away from the light source
  2. put the pondweed into the boiling tube (cut end at the top). Push it down (gently) with a glass rod
  3. leave for 5 minutes
  4. start the stop watch, count the number of bubbles produced in 1 minute. Record the result in the Table
  5. react the count twice more. Calculate the mean number of bubbles per minute
  6. react all the steps with the test tube rack and boiling tube at distances of 20cm, 30cm and 40cm from the light source

GCSE B1 (15 decks)

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