Organisation in plants Flashcards

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1
Q

Give the levels of organisation in plants, starting with organelles.

A

organelles, cells, tissues, organs, organ systems, organisms

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2
Q

What tissues are the leaf made up of?

A

Epidermis, palisade mesophyll, spongy mesophyll, xylem and phloem tissues

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3
Q

What is the function of the epidermis in the leaf?

A
  • location and guard cells and stomata.
  • upper epidermis cells are thin and transparent so sunlight can pass through to the palisade layer.
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4
Q

What covers the epidermal tissues and what is its function?

A

The Waxy cuticle:
- helps reduce water loss by evaporation.
-prevents leaf from being damaged form the heat of the suns rays, and damage form insects

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5
Q

The palisade layer has a lot of what organelle and what is its function?

A

Chloroplast:
- site of photosynthesis.
- Chloroplast contain a special pigment called chlorophyll that is essential for photosynthesis - - They are also at the top of the leaf where they can get most sunlight

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6
Q

What is the function of the spongy mesophyll?

A
  • only contain few chloroplast
  • Contains big pockets of air spaces which are essential for gas exchange
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7
Q

What is the function of meristem tissues?

A
  • found at the growing tips of shoots and roots and is able to differentiate (change) into lots of different types of plant cell, allowing plant to grow
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8
Q

Function of the lower epidermis?

A
  • found on the underside of the leaf
  • location of stomata and guard cells
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9
Q

Function of the stomata?

A
  • tiny pores found between two guard cells
  • widen and narrow to control gas exchange and water vapour loss
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10
Q

Function of the guard cells?

A
  • take in or lose water by osmosis
  • swell and open or close stomata
  • controlling gas exchange and water vapour loss
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11
Q

How does potassium effect guard cells

A
  • when plants have adequate potassium
  • potassium ions (k+) increase the concentration of the solution inside the guard cell.
  • causes water to move into the guard cells from more dilute areas by osmosis.
  • The additional water leads to the guard cells swelling unevenly because the thicker, inner walls are less flexible than the thinner, outer walls.
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12
Q

How are guards cells adapted to open and close?

A
  • when plant has lots of water the guards cells fill up with it and go plump and turgid
  • This makes stomata open so gases can be exchanged for photosynthesis
  • when the plant is short of water, the guards cells lose water and become flaccid, making the stomata close. This helps stop too much water vapour form escaping.
  • **thin outer walls and thickened inner walls make the opening and closing work
  • they are also sensitive to light and close at night to save water without losing out on photosynthesis
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13
Q

What are substances that can diffuse through the stomata? Name 3.

A
  • oxygen: diffuses out of leaf
  • carbon dioxide: diffuses into the leaf
  • water vapour: diffuses out of the leaf
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14
Q

What is the function of the xylem?

A

the xylem is a tissue which transports water and minerals from the roots up the plant stem and into the leaves.

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15
Q

How is the xylem adapted for its function?

A
  • A tube of dead cells , strengthened by lignin
  • no end walls* to create a continuous tube that allows water to move up through the transpiration stream
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16
Q

How are phloem adapted to their function?

A
  • cytoplasm moves from one cell to another to move sucrose and amino acids.
  • sieve plates between cells have holes in to allow cytoplasm movement. They also have no nucleus.
  • companion cells: transport substances in the phloem requires energy. One more more companion cells is attached to each sieve tube to provide this energy. A sieve tube is completely dependent on its companion cell.
17
Q

What is the function of companion cells?

A
  • Companion cells have lots of mitochondria which allows them to carry out cellular respiration at a high rate and, hence, release lots of energy
18
Q

Which is on the top of the leaf arrangement, xylem or phloem?

A

Xylem

19
Q

Which are on the outside of the arrangement, xylem or phloem?

A

Phloem

20
Q

What is transpiration?

A

Water evaporates from the surface of the mesophyll cells into the air spaces and the water vapour diffuses through the stomata.

21
Q

Name four conditions can cause the rate of transpiration to increase:

A
  • warmer air temperatures
  • higher light intensity
  • less humidity (less humid atmosphere outside the leaf)
  • increasing air movement
22
Q

Why do the stomata need to close when the plant is not taking in enough water?

A

to prevent wilting

23
Q

What is the transpiration stream?

A
  • plant takes up water form the soil by osmosis through their roots which are covered in root hair cells
  • water moves up the plant through the xylem
  • plants lose water vapour from the underside of their leaves through the stomata
  • This loss of water vapour is called evaporation. This drives the transpiration stream
24
Q

Why does increasing the temperature increase the rate of transpiration?

A

as environment temperature increases the kinetic energy of water vapour molecules increases
water vapour molecules diffuse and evaporate faster

25
Q

Why does increasing the air movement increase the rate of transpiration?

A

wind blows the water vapour molecules away from the underside of the leaf
- this maintains a steep concentration gradient between the air spaces in the leaf and external atmosphere
- cause water vapour to diffuse down the concentration gradient at a faster rate

26
Q

Why does decreasing the humidity increase the rate of transpiration?

A

less water vapour outside the leaf. Maintain steeper concentration gradient water vapour diffuses faster

27
Q

Why does increasing the light intensity increase the rate of transpiration?

A
27
Q

Why does increasing the light intensity increase the rate of transpiration?

A

as light intensity increase: stomata opens wider to obtain more carbon dioxide for photosynthesis . This increases diffusion rate of water vapour molecules.

28
Q

What is translocation?

A

the movement of sugar (sucrose and amino acids) produced by photosynthesis in the leaves(sources) to all other parts of the plant for respiration, immediate use or storage (sinks)

29
Q

What is the sugar transported in translocation used for?

A

respiration or converted to starch and stored

30
Q

How does a simple/bubble potometer work?

A

an air bubble is formed in a capillary tube which links to a beaker of water with a shoot in it. as the plant takes in water through its stem, the air bubble moves up the tube. you can measure how far it moves to see the rate of water uptake.

31
Q

Why is oil placed on top of the water on a mass potometer?

A

to prevent the evaporation from the surface of the water