Plants Flashcards

1
Q

What is the equation for photosynthesis?

A

6CO2 + 6H2O ——> C6H12O6 + 6O2

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2
Q

What type of reaction is photosynthesis?

A

Endothermic

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3
Q

Name 3 limiting factors on the rate of photosynthesis

A
  • Temperature
  • Light intensity
  • CO2 concentration
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4
Q

Compare the relationship between the rate of photosynthesis and light intensity

A

They are directly proportional

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5
Q

Compare the relationship between the rate of photosynthesis and distance away from light

A

They are inversely proportional

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6
Q

Photosynthetic organisms are the main producers of ____ and therefore _______

A

Food, biomass

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7
Q

Name 3 ways a plant is adapted to maximise photosynthesis

A
  • Large surface area to maximise light absorption
  • Thin for gases to reach cells easily
  • Have stomata for gas exchange
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8
Q

What are xerophytes?

A

Plants adapted to live in extreme environments

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9
Q

Describe some adaptations of a xerophyte

A

Cacti:

  • Have spines with small surface area and very thick waxy cuticle to reduce water loss
  • Less stomata to reduce water loss by transpiration
  • Spines also for protection
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10
Q

What is the waxy cuticle?

A

Waterproof layer of the plant

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11
Q

What is the epidermis?

A

The protective layer of the plant

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12
Q

What is the palisade layer of a plant?

A

Where light is absorbed

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13
Q

What is the spongy mesophyll for?

A

Taking in CO2 and releasing oxygen

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14
Q

What are stomata and guard cells for?

A

For allowing gas exchange and controlling water loss

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15
Q

Explain how the stomata open and close

A
  • Guard cells take in water by osmosis and become turgid, causing the stoma to open
  • When it is dark guard cells lose water and become flaccid, closing the stoma
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16
Q

The light intensity 20cm from a lamp is 600 lux, calculate the the light intensity 40cm away using inverse square law

A

Calculate how much further away the distance is

40/20 = 2 Therefore x2 further away

Then find the inverse of that and square it

2-1 = 1/2
(1/2)2 = 1/4

Lastly, multiply by the original amount

600 x 1/4 = 150 lux

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17
Q

Describe the effect of light intensity on the rate of photosynthesis

A

As the light intensity increases, the rate if photosynthesis increases this happens until a limiting factor causes the rate to stop increasing

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18
Q

Describe the effect of rate of CO2 concentration on the rate of photosynthesis

A

As the CO2 concentration increases, the rate if photosynthesis increases this happens until a limiting factor causes the rate to stop increasing

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19
Q

Describe the effect of temperature on the rate of photosynthesis

A

As the temperature increases, the rate if photosynthesis increases, this will happen until the optimum temperature is reached and the enzymes involved will denature

20
Q

How are root hair cells adapted to better absorb water and mineral ions?

A
  • Has a large surface area to increase rate of absorption
  • Has lots of mitochondria to gain more energy through aerobic respiration for active transport in translocation
21
Q

What is transpiration?

A

Movement of water and minerals up the xylem vessel

22
Q

What is translocation?

A

Movements of dissolved sugars up and down the phloem

23
Q

What happens in transpiration?

A
  • Water in the soil passes into the root hair cells by osmosis
  • The water then passes into the xylem vessel by osmosis
  • The water is transported to the leaves
  • The water evaporates through the stoma
24
Q

What are the factors that affect the rate of transpiration?

A
  • Temperature
  • Humidity
  • Wind speed
  • Light intensity
25
Q

How does temperature affect the rate of transpiration?

A

The warmer it is, the faster water evaporates through the stoma so more water needs to be absorbed at the roots

26
Q

How does humidity affect the rate of transpiration?

A

The lower the humidity, the faster the water evaporates due to diffusion so more water needs to be absorbed at the roots

27
Q

How does wind speed affect the rate of transpiration?

A

The windier it is, the faster the rate of diffusion of water molecules from the leaf so more water needs to be absorbed at the roots

28
Q

How does light intensity affect the rate of transpiration?

A

When it is light, the stomata are open, increasing the water loss by evaporation so more water needs to be absorbed at the roots

29
Q

Describe the structure of a xylem vessel

A

Hollow tube made up of dead cells, strengthened by lignin

30
Q

Describe the structure of the phloem

A

Tube with sieve plates surrounded by companion cells

31
Q

What sugar is transported in translocation?

A

Sucrose

32
Q

What does a potometer do?

A

Mesure the rate of transpiration in cm3/min

33
Q

What do auxins do?

A

Cause cells to elongate in the shoots and inhibit growth in the roots

34
Q

What is phototropism?

A

Growing in response to light

35
Q

What is gravitropism?

A

Growing in response to gravity

36
Q

What is another name for gravitropism?

A

Geotropism

37
Q

What is positive phototropism?

A

Growing towards light

38
Q

What is negative phototropism?

A

Growing away from light

39
Q

What is positive gravitropism?

A

Growing in the direction of gravity

40
Q

What is negative gravitropism?

A

Growing in the direction away from gravity

41
Q

What do gibberellins do?

A
  • Increase the speed of seed germination
  • Promote flowering
  • Cause some plants to fruit without being pollinated (causing seedless fruits)
42
Q

What is ethene for?

A

Ripening fruit

43
Q

Name 3 plant hormones

A
  • Auxins
  • Gibberellins
  • Ethene
44
Q

What are companion cells in the phloem for?

A

To provide energy for active transport

45
Q

What is the inverse square law?

A

1

d2