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Edexcel Gcse Biology > Paper 2 - Topic 6, Plant Structures And Their Function > Flashcards

Paper 2 - Topic 6, Plant Structures And Their Function Flashcards

1
Q

What are auxins

A

A group of plant hormones that inhibit growth in plant roots and stimulate growth in shoot tips

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2
Q

What is biomass

A

The total mass of organic material, measure in a specific area over a set period

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3
Q

Which hormone stimulates ripening in fruits

A

Ethene

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4
Q

What is gravitropism

A

A plants growth response to gravity

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5
Q

What are guard cells

A

Cells that surround the stomata and change shape depending on the volume of water, they control the rate of transpiration by becoming turgid or flaccid

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6
Q

What is lignin

A

A material that strengthens the walls of xylem cells

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7
Q

What is a limiting factor

A

A variable that limits the rate of a particular reaction

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8
Q

What is the lower epidermis

A

A layer of cells on the leaf’s lower surface that contains stomata and guard cells

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9
Q

What is negative plant tropism

A

The growth of a plant away from a stimulus

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10
Q

What is the palisade mesophyll layer

A

The main photosynthesis tissue in plants located below the upper endodermis, it receives the most light so contains the greatest concentration of chloroplasts

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11
Q

What is the phloem

A

A transport tissue found in plants that is specialised to transport sugars from the leaf to the rest of the plant in both directions

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12
Q

What is photosynthesis

A

An endothermic reaction that takes place inside photosynthetic organisms and converts light energy into chemical energy

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13
Q

What is the equation for photosynthesis

A

6CO2 + 6H2 ——> C6H12O6 + 6O2

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14
Q

What is phototropism

A

A plants growth response to light

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15
Q

What is plant tropism

A

The growth response of a plant to a stimulus

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16
Q

What are root hair cells

A

Specialised cells responsible for the uptake of water and minerals from the soil, they have long hair-like extensions known as root hairs, provide a large surface area for absorption

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17
Q

What is the spongy mesophyll layer

A

A type of loosely packed mesophyll tissue with air pockets specialised for gas exchange, also contains chloroplasts for photosynthesis

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18
Q

What is the stomata

A

Small holes found on the surface of a plant that can be opened or closed by guard cells to control water loss and gas exchange

19
Q

What is translocation

A

The movement of sugars up and down a plant from photosynthetic to non-photosynthetic tissues via the phloem

20
Q

What’s transpiration

A

Water loss from plant leaves and shoots via diffusion and evaporation

21
Q

What is the rate of transpiration affected by

A

Light intensity, temperature and air flow

22
Q

What is the upper epidermis

A

A layer of transparent cells that allows light to strike the palisade mesophyll tissue

23
Q

What’s the waxy cuticle

A

A waxy layer that reduces water loss from the surface of leaves

24
Q

What’s the xylem

A

A transport tissue in plants that is specialised to transport water and dissolved materials from the roots of the plants to the leaves

25
Q

What’s the word equation for photosynthesis

A

Carbon dioxide + water ——> glucose + oxygen

26
Q

How does temperature affect the rate of photosynthesis

A

-Increase in temp, rate of photosynthesis increases
- reaction is controlled by enzymes so only continues up till a certain temp before enzyme denatures

27
Q

How does light intensity affect the rate of photosynthesis

A

Higher the light intensity, the faster the rate of rsa toon

28
Q

How does carbon dioxide concentration affect the rate of photosynthesis

A
  • carbon dioxide is needed to make glucose so as concentration of carbon dioxide increases the rate of reaction increases
29
Q

How can you measure the oxygen production of a plant and calculate the rate of photosynthesis

A
  • pondweed placed in test tube full of water, top is sealed with a bung. A capillary tube also containing water leads into the test tube and is attached to a syringe
  • a lamp is placed at a measure distance from the test tube
  • as it photosynthesises, oxygen is produced forming gas in the capillary tube
    -distance bubble has moved is measure using a ruler to calculate volume of oxygen produced
  • variables that can be changed : temp (using water bath) time pondweed is left, light intensity (distance of lamp from plant)
  • control all factors that may affect photosynthesis apart from IV
30
Q

How are root hair cells adapted to its specific function

A
  • specialised to take up water by osmosis and mineral ions by active transport from the soil as they are found in the tips of roots
  • have large SA due to root hairs (more water can move in)
31
Q

How are xylem cells adapted to their specific function

A
  • ## specialised to transport water and mineral ions up the plant from roots to shoots
32
Q

How are phloem cells adapted to their specific function

A

Specialised to carry products of photosynthesis to all parts of the plant

33
Q

Why do plants loose water

A

Through transpiration, as the stomata’s are open, water evaporates at the open stomata on the leafs surface

34
Q

What do the guard cells do when lots of water is available to the plant

A

The cells fill and change shape opening the stomata (they are also light sensitive), this allows gases to be exchanged and more water leave the plant via evaporation
- more stomata found on bottom of leaf as cool and shaded so there is less water loss

35
Q

Where does translocation occur

A

Only in the phloem

36
Q

What are the adaptations of a leaf

A
  • stomata: able to close to minimise water loss and open to increase evaporation and transpiration also allows gas exchange to occur when open
  • chlorophyll: chlorophyll = green most efficient colour for absorbing light
  • ss: leaves are very thin so there is a short distance for carbon dioxide to enter the leaf and short distance for oxygen to diffuse out
  • large surface area: leaf can absorb more light at once
37
Q

How does an increase in temperature affect the rate of water uptake and transpiration

A
  • molecules move faster, evaporation happening at a faster rate so transpiration increases
  • rate of photosynthesis increase, more stomata are open for gaseous exchange, so more water evaporates and rate of transpiration increases
38
Q

How does an increase in relative humidity affect the rate of water uptake and transpiration

A

If relative humidity is high, there will be reduced concentration gradient between concentrations of water and vapour inside and outside leaf, resulting in slower rate of diffusion and decrease in rate of transpiration

39
Q

How does an increase air movements (wind) affect the rate of water uptake and transpiration

A
  • if air moving away from leaf, concentration of water vapour surrounding leaf will be lower
  • there is a steeper concentration gradient resulting in diffusion happening faster, increasing rate of transpiration
40
Q

How does an increase in light intensity affect the rate of water uptake and transpiration

A
  • increased rate of photosynthesis, so more stomata open, more water can evaporate and and increased rate of transpiration
41
Q

How do most plants show positive phototropism when they grow towards a light source

A
  • plant exposed to light on one side
  • auxin (growth hormone) moves to shaded side of root
  • auxin stimulates cells to grow more here
  • shoot bends towards light
  • plant receives more light so faster rate of photosynthesis
42
Q

How do most shoots show negative gravitropism as they grow away from gravity

A
  • auxin moves to lower side
  • cells of the shoot grow more on the side with most auxin
  • makes shoot bend and grow away from ground
43
Q

How do most roots show positive gravitropism as they grow towards gravity

A
  • auxin moves to lower side
  • cells of the root grow more on side with less auxin
  • makes the root bend and grow downwards

Edexcel Gcse Biology (9 decks)

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