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Biology > CB6- Plant Structures And Their Functions > Flashcards

CB6- Plant Structures And Their Functions Flashcards

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1
Q

What is photosynthesis?

A

Photosynthesis is the process of plants receiving light energy from the sun in order to create glucose for energy.

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2
Q

What is the glucose from photosynthesis used for?

A

Glucose can be used to make larger, complex molecules (this makes up the biomass) or it can be stored in the biomass so that it could be used later, or so that it can make its way through the food chain (when other animals eat the plants they will receive the energy).

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3
Q

What is the biomass?

A

All the materials in an organism.

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4
Q

How does photosynthesis link to the food chain

A
  • photosynthesis is producer of food for all life on earth
  • the food chain begins at plants and predators above plants receive all their energy from the glucose stored in plants
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5
Q

Where does photosynthesis occur?

A

It occurs in the chloroplast which contains a green pigment called chlorophyll that absorbs light.

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6
Q

What is the word equation for photosynthesis?

A

Carbon dioxide + water —> glucose + oxygen

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7
Q

What is the balanced symbol equation for photosynthesis?

A

6CO2 + 6H20 —> C6H1206 + 6O2

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8
Q

Is photosynthesis endothermic or exothermic?

A
  • Photosynthesis is an endothermic reaction because it absorbs energy from the sun.
  • the products have more energy than the reactants
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9
Q

What does the glucose exactly do once made in plants?

A
  • linked together to form a polymer called starch
  • this starch stays in the chloroplast until photosynthesis stops
  • the starch can then be broken down into smaller, simpler substances
  • these can then be moved into the cytoplasm to make sucrose
  • sucrose is then transported around the plant via the phloem vessels
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10
Q

What is sucrose used for in plants?

A
  • sucrose can be turned into starch for storage purposes
  • other molecules such as proteins, lipids, or cellulose
  • glucose for respiration
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11
Q

What are the three main factors than affect photosynthesis?

A
  • light intensity
  • temperature
  • co2 concentration
  • chlorophyll concentration
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12
Q

How does light intensity affect photosynthesis?

A
  • photosynthesis depends on energy from the sun so more light will provide more energy
  • at first when light levels are raised the rate of photosynthesis will increase constantly but at a certain point it will stop rising
  • this means that there is another limiting factor stopping the rate from increasing
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13
Q

How does chlorophyll concentration affect the rate of photosynthesis?

A
  • chlorophyll absorbs sunlight so less of this in a plant, will make it struggle to carry out photosynthesis
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14
Q

How could photosynthesis levels differ in a plant?

A
  • disease
  • lack of nutrients
  • environmental stress
    These factors all damage the chloroplast, making it more difficult to produce chlorophyll
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15
Q

How does carbon dioxide levels affect photosynthesis?

A
  • carbon dioxide is a reactant in photosynthesis, so the more there is the easier photosynthesis will be carried out.
  • on a graph photosynthesis rates will increase while co2 levels increase but at a certain point the graph will stop increasing and this means that something else is the limiting factor
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16
Q

How does temperature affect photosynthesis?

A
  • as temperatures increase the enzymes within plants become more active as-well as the particles, therefore increasing the rate of reaction.
  • on a graph this would be represented at a curve because the rate of photosynthesis would increase with more active enzymes, however once the enzymes reach their optimum temperature they will denature and no longer function
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17
Q

Explain two toned graphs in photosynthesis.

A
  • Some graphs may display two separate lines for different temperatures or co2 concentrations.
  • one line will usually plateau faster, showing what different factor would be limiting the rate of photosynthesis.
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18
Q

Explain inverse proportion in light intensity.

A
  • the distance from the lamp and light intensity are inversely proportional
  • as distance increases light intensity decreases because when light is closer to a plant, it will be more concentrated
  • light intensity decreases in proportion to the square of the distance
  • light intensity = 1 / distance ^2
  • if the distance were divided by two the light intensity would be 4 times greater
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19
Q

How do you investigate light intensity?

A
  1. Have an led light source
  2. Have multiple boiling tubes with sodium hydroxide carbonate
  3. Put pondweed or a photosynthesising organism in the tube with a cut end on the top
  4. Let this adjust to conditions for 5 mins
  5. Oxygen bubbles will begin to produce and you need to count these
  6. Repeat at different distances from the lamp.

OR
1. Have multiple test tubes of the organism inside sodium hydrogen carbindicator and put them at different distances from the lamp
2. The indicator will change colour based on the light intensity
3. Compare these on a ph scale

(You can also have a controlled test tube which is covered by tin foil)

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20
Q

Why is an led light source used and not a regular one?

A
  • it does not release much heat
  • if too much heat is exposed it could alter the experiment making it based on temperature
  • if only a normal light source is available you have to place a beaker of water between the light source and other test tubes so that it will absorb the heat
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21
Q

Why is sodium hydrogen carbonate solution used?

A
  • it releases carbon dioxide which stimulates photosynthesis
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22
Q

What are some downsides to the experiment?

A
  • the bubbles are not always the same size and some will contain more oxygen than others but they will still be considered equal
  • bubbles may be too fast to count
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23
Q

How can you make the bubble experiment more accurate?

A
  • use a gas syringe to accurately measure the volume of oxygen produced
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24
Q

What is the dependant variable in the experiment?

A
  • the variable that we measure is the volume of oxygen or the ph levels
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25
Q

What is the independent variable?

A

The thing that we change is the distance from the lamp that influences the volume of oxygen/ or the ph

26
Q

How do greenhouses help photosynthesis?

A
  • greenhouses allow for the best growth in plants
  • traps the suns heat creating an optimum temperature
  • artificial light allows photosynthesis to happen night and day
  • paraffin heaters can be used to pump in co2 but also increase the temperatures
  • enclosed spaces, keeping out pests and pathogens.
  • fertiliser can be used to give the pants minerals
  • pesticides keep out unwanted bugs
27
Q

What is the function of a root hair cell?

A
  • designed to absorb water and mineral ions
28
Q

Describe a root hair cell.

A
  • they are are cells on the surface of plant roots which stick out into the soil
  • because they stick out into the soil, the overall surface area of the plant increases, maximising the rate of absorption
  • they have very thin cell walls for easy absorption
29
Q

What type of transport occurs from the mineral ions outside the root hair cells to the inside?

A
  • active transport occurs because the concentration on mineral ions inside the root hair cell in higher than the outside
30
Q

What type of transport occurs from the water outside the root hair cell to inside?

A
  • osmosis occurs because the concentration of water outside the cell is higher than the concentration within
31
Q

What is a concentration gradient?

A

A concentration gradient is present when two spaces are connected and have the same volume but different concentrations of a substance.

32
Q

Since leaves are the site of photosynthesis, how does it get carbon dioxide and water?

A
  • carbon dioxide enters directly from the outside of the leave via the stomata which is underneath along the lower eperdermis
  • water comes from the roots in the soil and is transported throughout the leaf by the xylem vessels
33
Q

What is the structure of a leaf like?

A

The leaf contains:
- Waxy cuticle at the top of the leaf
- the upper eperdermis
- the palisade mesophyll layer
- the spongy mesophyll layer
-the lower eperdermis

34
Q

Why does the leaf have a waxy cuticle?

A
  • having a waxy cuticle, reduces water loss by being waterproof and preventing water from passing through
35
Q

Describe the upper eperdermis?

A
  • contains epidermal tissue which is almost transparent because the sunlight at the top of the leaf must hit it
36
Q

Describe the palisade mesophyll layer.

A
  • contains palisade cells which are packed with chloroplast
37
Q

Describe the spongy mesophyll layer.

A
  • contains lots of gaps so that the gas can easily diffuse to the palisade mesophyll layer
38
Q

Describe the lower eperdermis.

A
  • The lower eperdermis contains lots of stomata which is where co2 enters to travel up to the spongy mesophyll layer
  • the stomata also have guard cells which close when there is limited water supply and open when there is plentiful
39
Q

Why is the stomata underneath the leaf?

A
  • the stomata is at the underside because it is more shaded, making it cooler and less likely to have water evaporation causing water loss in the plants
40
Q

Describe guard cells in more depth.

A
  • since the stomata is the main problem for water loss due to the gaps creating easy escape points they have guard cells
  • when the plant has a lot of water, the guard cells will be turgid as they are well hydrated and do not need to worry about water loss, therefore can be open
  • when the plant has limited water it will be flaccid so the stomata will close in order to try and conserve the water vapour inside
41
Q

Why do guard cells close at night?

A
  • photosynthesis does not occur at night since there is no sunlight so they do not need to be open, potentially causing water loss.
    -the stoma aims to leave the stomata open for as short a time as possible so they can maximise co2 absorption while reducing water loss.
42
Q

What is the meristem?

A
  • the meristems are found at the growing tips of roots and shoots and can differentiate into lots of different cell types for growth and repair.
43
Q

What is the phloem vessel?

A
  • a type of transport vessel that transports food substances like sucrose made in the leaves into other parts of the plant
  • made of columns of elongated living cells with small pores in the END WALLS to allow substances to flow through
  • transport can occur in both directions
  • this movement is called TRANSLOCATION and requires energy from translocation to work.
44
Q

What can the sucrose from translocation be used for?

A
  • they can be used for immediate use or storage for later on
45
Q

What is the xylem vessel?

A
  • a type of transport vessel that transports water and mineral ions from the roots to the stems and leaves
  • made of dead, hollow cells joined from end to end with NO END WALLS and just one long hole
  • inside there is an unbroken chain of water due to weak forces of attraction between water molecules.
  • they are strengthened by lignin
  • this movement of water from the roots to the rest of the plant is called the TRANSPIRATION stream
46
Q

Explain the transpiration stream.

A
  • transpiration is the loss of water from plants which occurs at the leaves
  • this slight loss of water creates a shortage which the xylem vessel will quickly replace
  • this creates a constant stream of transpiration along the plant (this also carries mineral ions that have been dissolved in the water).
47
Q

What is the water absorbed by plant roots used for?

A
  • Carrying dissolved mineral ions
  • keeping cells rigid
  • cooling the leaves with evaporation
  • photosynthesis
48
Q

What is diffusion?

A

When particles move from an area of high concentration to an area of low concentration down a concentration gradient.

49
Q

What is osmosis?

A

The net movement of water particles across a semi permeable membrane from an area of high concentration to an area of low concentration across a concentration gradient.

50
Q

What is active transport?

A

When particles/ molecules in a substance goes from an area of high concentration to low concentration up a concentration gradient

51
Q

What 4 factors can affect transpiration rates?

A
  • light intensity
  • temperature
  • air flow
  • humidity
52
Q

How does light intensity affect transpiration?

A
  • more light = more photosynthesis
  • this means that the stomata will be open more often to allow co2 to come inside
  • there will be more water loss, triggering more transpiration.
53
Q

How does temperature affect transpiration?

A
  • the warmer it is, the higher the rate of transpiration
  • water particles will have more energy to evaporate and diffuse out of the stomata
54
Q

How does air flow affect transpiration?

A
  • better airflow around a plant increases the rate of transpiration
  • this is because a low concentration will be maintained around a plant allowing diffusion to occur
55
Q

How does humidity affect transpiration?

A
  • humidity is a measure of how much water vapour is in the air
  • humid air decreases the rate of transpiration because the large amount of water vapour in the air creates a high concentration around the plant, stopping diffusion.
56
Q

How can a potometer be used to measure transpiration rates?

A
  • potometers measure water uptake by a plant by showing the distance that air bubbles move across a capillary tube
  • the plant will take up water causing a bubble to move across a capillary tube towards it
57
Q

What are the main uses of glucose in plants?

A
  • cellular respiration- break down the glucose to release energy
  • make cellulose- which is used to make strong cell walls
  • make starch- which is used to store glucose for a later time
  • make amino acids- which are used to make proteins
  • make lipids- these store the energy as fats or oils for later use
58
Q

Why is starch a useful long term storage molecule?

A
  • it is insoluble in water
  • it is compact
  • it can easily be broken down when needed
59
Q

how are leaves adapted to their functions?

A
  • broad and flat providing a large surface area ad a small surface area to volume ratio
  • leaves are thin providing a short diffusion distance
60
Q

what are companion cells?

A
  • companion cells are found in phloem vessels and pump sucrose in and out of the sieve tubes that are connected via pores

Biology (9 decks)

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