Plants Flashcards

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1
Q

Palisades mesophyll

A

tightly packed cells containing chloroplasts

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2
Q

Spongy mesophyll

A

loosely arranged cells with lots of intercellular spaces.

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3
Q

Stomata

A

Openings in leaves that lead to air spaces.

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4
Q

Transpiration

A

The loss of water through stomata in plants

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5
Q

Guard cells

A

specialized leaf cells that control the opening and closing of stomata

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6
Q

Sunken stomata

A

Stomata that are sunken in order to decrease the rate of wind-caused transpiration

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7
Q

Flowers

A

Reproductive organs of plants

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8
Q

How does gas exchange in plants work?

A
  1. Stomata lets CO2 diffuse into the leaf
  2. CO2 diffuses into the water lining the leaf
  3. CO2 enters photosynthesizing cells
  4. O2 enters through gas pockets in soil, allowing the plant to perform respiration.
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9
Q

How do guard cells work?

A
  1. An electrical gradient is established
  2. An osmotic gradient is established
  3. Water enters the guard cell and the stomata open
  4. Water leaves, stomata closes
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10
Q

What are the two types of tissue involved in transport of materials in plants?

A

Xylem and phloem

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11
Q

Xylem tissue

A

Transports water and minerals, and provides mechanical support. Basically columns of cell-wall-ness (the cells are technically dead)

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12
Q

Phloem tissue

A

Transports the products of organic materials, like sugars.

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13
Q

How is water’s movement through xylem explained?

A

Cohesion-tension theory: TACT. Transpiration, Adhesion (attraction between different substances), Cohesion (attraction between the same substance to itself), Tension (which is created as water moves out of the leaf, pulling more water in)

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14
Q

Plasmolysis

A

the contraction of the cell away from the cell wall (In plants). Occurs when not enough water is available.

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15
Q

Cell turgor

A

Rigidity caused by the amount of water in a plant cell

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16
Q

What gas causes ripening?

A

Ethylene. Positive feedback; as the fruit ripens, more ethylene is released.

17
Q

Abiotic

A

non-living

18
Q

Describe the process of phototropism

A

Phototropism is plants’ response to light. Auxin is a growth hormone that causes lengthening. When light is unequal on the plant stem, auxin goes to the shady side, causing the plant to bend towards the light

19
Q

What is gravitropism?

A

Plants’ response to gravity

20
Q

What is thigmotropism?

A

Plants’ response to touch

21
Q

Dormancy (plants)

A

Response to unfavourable conditions. Abscission is the loss of leaves or other parts, and Seed Dormancy is a mechanism that allows seeds to delay germination until they have ideal conditions.

22
Q

On what stimuli does seed germination rely?

A
  1. Water
  2. Oxygen
  3. Temperature (optimal)
  4. Fire! Nutrients from burnt stuff, more light for seedlings
  5. Hormones
23
Q

Photoperiodism

A

The response of plants to changes in the photoperiod, the relative length of day vs. night time.

24
Q

Do plants have circadian rhythms?

A

Yup.

25
Q

How do plants maintain their circadian rhythms?

A

Two forms of phytochrome that convert from one to the other.

  1. P(r) is synthesized in plant cells
  2. P(fr) is the active form
  3. P(fr) accumulates during the day as P(r) is exposed to 660 nm wavelength light (Red light).
  4. P(r) accumulates at night as it’s not converted
  5. At daybreak, P(r) is rapidly converted to P(fr)
  6. Night length resets the circadian rhythms.
26
Q

When do different plants flower?

A
  1. Long day plants flower when daylight is increasing
  2. Short day plants flower in late summer when daylight is decreasing
  3. Day neutral plants don’t care. They care about some other stimuli
27
Q

Structural defenses of plants

A

Stickyness, spines, etc.

28
Q

Chemical defenses of plants

A

Toxins! (like caffeine or nicotine) that kill insects