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Biology > Topic 6 - Plant Structures And Their Functions > Flashcards

Topic 6 - Plant Structures And Their Functions Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What do plants use to make their own food?

A

Photosynthesis

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2
Q

In what subcellular structure does photosynthesis happen inside of?

A

Photosynthesis happens inside of the chloroplasts, they contain chlorophyll which absorb the light.

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3
Q

Word equation for photosynthesis …
Symbol equation

A
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4
Q

Is photosynthesis an endothermic or extothermic reaction?

A

Photosynthesis is an endothermic reaction. Energy is taken in

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5
Q

What is the rate of photosynthesis affected by?

A

-light intensity

-the concentration of CO2

  • the temperature

-amount of chlorophyll

Any of these can become the limiting factor and stop photosynthesis from stopping any faster.

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6
Q

At what temperature do the enzymes needed for the photosynthesis reaction become denatured ?
What is the optimum temperature for a plant?

A

Around 45 degrees
Optimum - 21 degrees

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7
Q

What does not enough light do to the rate of photosynthesis?

A

It slows it down.

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8
Q

How’s energy transferred to the plant for photosynthesis ?

A

Light

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9
Q

What happens to the rate of photosynthesis as we increase light intensity?

A

As we increase light intensity , the rate of photosynthesis increases. They are directly proportional. However this is only up to a certain point.

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10
Q

How do we measure lights intensity?

A

Using a light meter

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11
Q

What happens to the light intensity as the distance of the lamp increases?

A

As the distance of the lamp increases, the light intensity decreases.

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12
Q

What is the inverse square law.
Light intensity ∝

A

Light intensity ∝ 1/ Distance (d)^2

∝means directly proportional to

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13
Q

What does the inverse square law mean?

A

If you halve the distance , the light intensity will be 4 times greater.

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14
Q

What happens to the rate of photosynthesis when we increase CO2 concentration?

A

The rate of photosynthesis is directly proportional to the CO2 concentration. It will increase up to a certain point until it’s no longer a limiting factor.

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15
Q

How do we test for starch in a leaf?
How do we know if there is starch present?

A

Do the iodine test
1) place leaf in boiling water for 30 seconds- This kills it and breaks down its cell wall.

2) place leaf in boiling ethanol- removes chlorophyll, making the leaf pale in colour. This is the control.

3)spread the leaf onto a white til and add iodine to test for the presence of starch.

We know there’s starch present if the iodine changes colour from yellow-brown to blue-black

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16
Q

How do root hairs take in minerals?

A

They use active transport as the ground around them usually has a low concentration of nutrients than in the plant roots. Mineral ions are absorbed through microscopic hairs on the roots of a cell.

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17
Q

How do root hairs take in water?

A

Using osmosis. The millions of microscopic hairs on the roots absorb the water using osmosis

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18
Q

What process does the phloem do?

A

The phloem does translocation

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19
Q

What are assimilates?
Main assimilate in plants

A

Assimilates is the mixture inside the phloem. It’s very hard to separate. Sucrose

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20
Q

What is the main assimilate in plants?

A

Sucrose NOT Glucose

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21
Q

What is translocation?

A

Translocation is the movement of assimilates made by plant cells along the phloem.

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22
Q

What is the ‘source’ in the phloem?

A

The source is anywhere sucrose is released into the phloem. It produces the energy

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23
Q

What is the ‘sink’ in the phloem?

A

The sink is anywhere sucrose is removed from the phloem. It steals energy

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24
Q

Source, sink or neither? Why?
Leaf in summer-
Developing bud-
Xylem-
Actively growing root tips-

A

Leaf in summer - source as it’s doing photosynthesis and making sugars
Developing bud- sink as it needs energy to grow
Xylem- neither as it’s not involved with the transport of sucrose
Actively growing root tip- source as it needs energy to grow

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25
Q

How do we get sugars into the phloem and transported within it? (5 steps)

A

1) companion cells use ATP to actively transport hydrogen ions into the surrounding tissue.

2) this creates a diffusion gradient with a high concentration of hydrogen ions outside the companion cells.

3)hydrogen ions move back into the companion cells and bring sucrose with them.

4)this causes the concentration of sucrose in the companion cells to increase

5)sucrose moves from the companion cells to the sieve tube elements using plasmodesmata

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26
Q

What do xylem tubes do?

A

Carry water and minerals up the plant.

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27
Q

What do xylem tubes do?

A

Carry water and minerals up the plant.

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28
Q

What process takes water up the plant?

A

Transpiration

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29
Q

What are xylem tubes made up off?
What material strengthens them?

A

Dead cells joined end to end with no end walls in between them and a hole in the middle. Strengthened with a material called lignin

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30
Q

What factors can affect transpiration rate ? And how?

A

-Temp , warm means the water particles have more energy to diffuse out the stomata

-light intensity, stomata open up more in the light.

-airflow(wind speed), if the airflow is poor water vapour surrounds the leaf, this means there’s a high concentration of water particles outside the leaf and diffusion happens slow

-surface area of the leaf

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31
Q

What can measure the transpiration rate, light intensity , temp or air flow?

A

A potometer measures any of these independently

32
Q

What’s the movement of water through the plant called?

A

The transpiration stream

33
Q

How does the water leave the leaves of a plant ?

A

Water leaves the leafes of a plant through transpiration.

34
Q

What takes ions and water up the plant?

A

The xylem

35
Q

How does the water enter the roots?

A

Through osmosis

36
Q

How do mineral ions enter the roots ?

A

Through active transport

37
Q

What are the 4 essential mineral ions in a plant ?

A

Nitrogen
Phosphate
Potassium
Magnesium

38
Q

Why do plants need nitrogen ?
Deficiency symptoms of plants without hydrogen?
Explanation.

A

Use - growth, adaptations to environments

Deficiency symptoms - short, spindly appearance that can lead to small leaf area

Explanation- overwatering can cause this

39
Q

Why do plants need phosphorus?
Deficiency symptoms of phosphorus?
Whay may cause a phosphorus deficiency?

A

1) phosphorus is essential for cell division and energy production.

2)short,spindly appearance

3)overwatering

40
Q

Why do plants need pottasium?
Pottasium deficiency symptoms?
What may cause a pottasium deficiency?

A

1) plants need pottasium for optimal growth and protein synthesis

2)brown scorching of leaf tips

3) extreme moisture or compaction decreases oxygen levels in the soil.

41
Q

What do plants need magnesium?
Symptoms of a magnesium deficiency in plants ?
Why may the deficiency happen?

A

1) enzyme activation and protein synthesis

2) yellowing , leaf veins

3) excess leeching of Mg nutrient

42
Q

What plant can be used to measure the rate of photosynthesis ?

A

Canadian pondweed

43
Q

What plant can be used to measure the rate of photosynthesis ?

A

Canadian pondweed

44
Q

How do we measure the rate of photosynthesis ?

A

Use the gas syringe to measure the volume of oxygen produced

45
Q

What does the loss of water in transpiration do?

A

Creates a shortage of water in the lead so more water is drawn up from the rest of the plant through xylem vessels to replace it.

46
Q

What does the transpiration stream carry along with it?

A

Mineral ions.

47
Q

What are stomata? What do they do?

A

-Stomata are tiny pores on the surface of a plant.
-Stomata allow C02 and oxygen to diffuse directly in and out of a leaf. .
-allow water vapour to escape during transpiration.

48
Q

How does the water leave the stomata?

A

Through diffusion.

49
Q

Why do leaves have a large surface area?

A

So they can capture more light which is needed for photosynthesis.

50
Q

What does the palisade layer have lots of? And where is located and why?

A

The palisade layer has lots of chloroplasts. It is located at the top of the lead so it can get the most light

51
Q

Why is the upper epidermis transparent?

A

So light can pass through it and get to the palisade layer.

52
Q

Why do epidermal tissues have a waxy coating?

A

To reduce water loss by evaporation.

53
Q

Why do plants have small leaves or spines instead of leaves?

A

Because this reduces the surface area for water loss by evaporation. Spines help stop animals eating the plant to get water.

54
Q

Who do some plants have thick waxy cuticles?

A

To reduce water loos by evaporation.

55
Q

Why do plants sometimes have fewer stomata or stomata that only open at night?

A

To reduce water loss by evaporation.

56
Q

What is the meristem?

A

The point where growth occurs in plant.

57
Q

What are auxins?

A

Auxins are plant hormones which control growth at the tips of roots and shoots.

58
Q

Where are auxins produced

A

The meristem produced auxins

59
Q

How do auxins move through the plant?

A

Auxins move through the plant in solution.

60
Q

How do auxins stimulate the cell elongation process?

A

By diffusing backwards auxins stimulate the cell elongation process

61
Q

What controls the plants growth response to light and gravity?

A

Auxins

62
Q

What does sunlight do to auxins?
What does this mean for the plant?

A

Sunlight destroys auxins.
In tbe sun the plant will start using auxins but in tbe shade the auxins will still get used and the plant may then bend towards the sunlight

63
Q

Definition of a hormone?
Where do they travel and what are they secreted by?

A

A hormone is a chemical messenger that coordinated systems.

Travel in tbe blood and are secreted by glands

64
Q

What does it mean if a shoot is negatively gravitropic?
How does this happen?

A

It grows away from gravity

When it’s growing sideways, gravity produces an uneven distribution of auxin in the tip, with more on the lower side. This causes the lower side to grow faster and bend the plant upwards.

65
Q

Why are shoots positively phototropic?

A

When it’s exposed to light it gets more auxins on the shaded side this makes the cells elongate faster on the shaded side. Causing the shoot to bend towards the light.

66
Q

Why are roots positively gravitropic?

A

Because it will have more auxin in its lower side as it’s growing sideways.
But in a root auxin stops growth, this means it will bend down

67
Q

Why are roots negatively phototropic If exposed to light ?

A

In roots auxins inhibit cell elongation so the root bends downwards when auxins accumulate on the shaded side.

68
Q

Common plant hormones and what do they do?

A

Prostaglandins - release stress signals in plants

Ethane- emitted by bananas and ripens other fruit

Gibberelins - create seedless fruits

69
Q

What is tropism?

A

Tropism is a growth response to a stimulus

70
Q

What are the 5 types of tropisms? (Growth response to a stimulus)

A

Phototropism
Geotropsim( gravitropsm)
Chemotropsim
Thigmotropism
Hydrotropsim

71
Q

What is the stimulus for phototropism?
Positive or negative in the roots and shoots? Explanation?

A

Light
Roots: negative tropism
Shoots:positive tropism

Roots grow away from light
Shoots grow towards light

72
Q

What is the stimulus for geotropism (gravitropism)?

Positive or negative in the roots and shoots? Explanation?

A

Gravity

Roots: positive geotropism
Shoots: negative gravitropism

Roots grow towards gravity
Shoots grow away from gravity

73
Q

What’s the stimulus for chemotropism?

Positive or negative in the roots and shoots? Explanation?

A

Chemicals

Roots- positive chemotropism because they’re trying to reach the chemicals in the soil

Shoots- negative chemotropism because they go up

74
Q

What’s the stimulus for thigmotropism?

Positive or negative in the roots and shoots? Explanation?

A

Movement/touch

Shoots- positive thigmotropism as it helps plants direct their direction of growth

Roots- negative thigmotropism as the roots need to avoid rocks etc.

75
Q

What’s the stimulus for hydrotropism?

Positive or negative in the roots? Explanation?

A

Water

Roots- positive hydrotropism because the roots get water for the plant

76
Q

where does transpiration happen?
Translocation?

A

Transpiration in the xylem
Translocation in the phloem

Biology (7 decks)

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