SB6 - Plant Structures And Their Functions

Question 1

How do plants and algae get energy

Answer 1

Trap energy transferred by the light from the sun

Energy transferred to glucose in photosynthesis - glucose and products made from it are stores of energy

Question 2

What is biomass

Answer 2

The materials in an organism are its biomass

Plants and algae produce their own and so produce their own food

They are producers in food chains

Question 3

What is photosynthesis simply

Answer 3

A series of chemical reactions catalysed by enzymes

Question 4

Tell me the word equation for photosynthesis

Answer 4

Carbon dioxide and water = glucose and oxygen

Question 5

Where does photosynthesis occur

Answer 5

In chloroplasts which contain a green substance called chlorophyll that traps energy transferred by light

Question 6

What type of reaction is photosynthesis

Answer 6

Endothermic reaction as energy enters from its surroundings and so products have more energy than reactants

Question 7

What happens to glucose molecules

Answer 7

Glucose molecules are linked to form a polymer starch - stays in chloroplasts until photosynthesis stops

Starch is broken down into simpler substances which move into cytoplasm to make sucrose

Question 8

What can sucrose be used for

Answer 8

It’s another type of sugar molecule

Sucrose is transported around the plant and may be used to make:

• starch (in a storage organ such as potato)
• other molecules for the plant (such as cellulose, lipids, or proteins)
• glucose for respiration (to release energy)

Question 9

Tell me about palisade cells

Answer 9

They are near the top of a Leaf packed with chloroplasts - adapted to allow leaf to absorb maximum light

Question 10

Tell me about stomata

Answer 10

Leaves contain microscopic pores called stomata or singular stoma

They allow carbon dioxide to diffuse into the leaf

Allow oxygen producer escape into the air and as well as water vapour

Question 11

Tell me about guard cells

Answer 11

The stomata are opened and closed by stomata

In the light, water flows into pairs of guard cells making them rigid

This opens the stoma

At night water flows out of the guard cells so they shut

Question 12

Why are leaves thin

Answer 12

So carbon dioxide does not have to diffuse far into the leaf

Question 13

What’s gas exchange

Answer 13

The flow of different gases into and out of a leaf eg carbon dioxide and oxygen

Question 14

What’s reduced concentration of air molecules

Answer 14

Causes a lower rate of photosynthesis in high mountains

Question 15

How can temperature affect rate of photosynthesis

Answer 15

The reactions in photosynthesis are catalysed by enzymes that work better in warmer conditions

Question 16

What’s the limiting factor

Answer 16

The factor that prevents a rate increasing

Carbon dioxide concentration, temperature and light intensity can be limiting factors

The maximum rate of photosynthesis is controlled by the factor in shortest supply

Question 17

What’s a linear relationship

Answer 17

Between two variables

Question 18

What’s direct proportion

Answer 18

If line in graph goes through the origin - it shows the two variables are in proportion

As one increases the other one does too

Question 19

What’s the inverse square law

Answer 19

Used to calculate new light intensity

1/new distance from light source ^2

Question 20

What is water absorbed by plant roots also used for

Answer 20

Carrying dissolved mineral ions

Keeping cells rigid - otherwise they will wilt (stems and leaves will droop)

Cooling the leaves - when it evaporates from them

Photosynthesis

Question 21

Tell me about root hair cells

Answer 21

The outer surfaces of many roots are covered with root hair cells

They are extensions to increase surface area so water and mineral ions can be quickly absorbed - also have thin walls so the flow of water into the cells is not slowed down

Question 22

Tell me about osmosis and diffusion

Answer 22

Particles Constantly move in random directions and so particles in a fluid diffuse down a concentration gradient

This is diffusion inside plant roots as the cell walls have an open structure allowing water particles to diffuse towards the middle of the root

Water passes into the cytoplasm of root hair cells by osmosis

Question 23

Tell me about active transport

Answer 23

Mineral salts are naturally occurring ionic compounds

Plants need the ions to from new substances

Eg nitrate ions are needed to make proteins

The concentration of ions in root hair cell is greater than in the soil

Proteins in the cell membrane pump the ions into the cell and so is an example of active transport

Question 24

What’s transpiration

Answer 24

The evaporation of water from leaves keeps them cool and helps dissolved mineral ions move up the plant

The flow of water into a root up the stem and out of the leaves is transpiration

Question 25

Tell me about xylem vessels

Answer 25

Xylem vessels form continuous pipes leading from a plants roots to its leaves Inside the vessels is an unbroken chain of water due to weak forces of attraction between water molecules Water is pulled up the xylem vessels in the stem as water evaporates from the xylem vessels in the leaves As the water vapour diffuses out of s leaf, more evaporates from the xylem vessel inside the leaf

Question 26

What makes diffusion faster

Answer 26

The bigger the difference between the concentrations makes it faster

Question 27

What factors increase transpiration But reduce concentration of water molecules outside the stomata

Answer 27

Wind moves water molecules away from the stomata Low humidity means little water in the air Higher temps so particles move faster and so will diffuse Greater light intensity - makes stomata wider

Question 28

Tell me about xylem

Answer 28

Xylem cells die and Thor top and bottom cell walls will disintegrate To create long empty vessels so water can move easily

Question 29

Why are xylem vessels rigid

Answer 29

Becuase they have thick side walls and rings of hard lignin and so water pressure inside the vessel does not burst or collapse on them The rigid xylem vessels also help to support the plant

Question 30

Tell me about phloem

Answer 30

Plants make sucrose and glucose and starch made in photosynthesis Sucrose is translocated in the sieve tubes of the phloem tissue - the large central channel in each sieve cell is connected to its neighbours by holes, through which sucrose solution flows

Question 31

What do companion cells do

Answer 31

They actively pump sucrose into or out of the sieve cells that form the sieve tubes As sucrose is pumped into sieve tubes, the increased pressure causes the sucrose solution to flow up to growing shoots or down to storage organs

Question 32

Why do leaves have large surface areas w

Answer 32

To collect enough light The energy transferred by light is trapped by chlorophyll packed into discs inside chloroplasts The energy is then transferred to glucose during photosynthesis The chloroplasts in a cell can move yoward or away from the light - as protection from bright light

Question 33

Why are leaves thin

Answer 33

So carbon dioxide does not have to diffuse far before reaching photosynthesising cells X Carbon dioxide diffuses through the Leaf through open stomata

Question 34

Tell me about spongy cells

Answer 34

They are irregularly shaped and do not fit together so air spaces are created - allowing gas to diffuse easily inside a leaf

Question 35

What supplies the water for photosynthesis

Answer 35

A network of xylem vessels

Question 36

Tell me the layers of a leaf starting from the bottom of the leaf

Answer 36

Cuticle Guard cells and stoma in the lower epidermis Layer constant spongy cells with xylem vessels, phloem tissue and air space Layer of palisade cells Upper epidermis Cuticle

Question 37

Tell me about epidermis cells

Answer 37

They form the outer layers of a leaf, holding the leaf together and protecting the cells inside They are transparent, allowing light to pass through them easily and also produce a waterproof waxy cuticle to help prevent water loss and stop microorganisms and water entering the leaf

Question 38

Tell me some adaptions of trees in cold environments

Answer 38

In winter many broad leaved deciduous plants lose all their leaves to prevent water loss when soul is frozen Most conifers don't do this and have needle shapes leaves with a much smaller surface area and very thick cuticle - this shape creates less wind resistance than broad leaves - allowing conifers to withstand high winds and collect less snow

Question 39

How can plants reduce water loss in hot environments

Answer 39

Trapping water vapour close to their leaves which slows the rate of diffusion out of leaves Conifers achieve this by having stomata located in small pits, where water collects Becuase it is less exposed to air movement Other plants use tiny hairs to trap water vapour

Question 40

Tell me some adaptions of cacti on dry environments

Answer 40

Some have hairs Spines instead of leaves to minimise surface area of the plant Cacti stomata only open at night Carbon dioxide is taken in at night and stored for use during the day Thick cuticle Stomata only found in valleys of the stem

Question 41

What is a stimulus

Answer 41

Change in environment that causes a response by an organism

Question 42

What's a tropism

Answer 42

Responding to a stimulus by growing towards or away from it

Question 43

What's a phototropism

Answer 43

A tropism towards the light is a positive phototropism A tropism away from the light are negatively phototropic

Question 44

Give an example of a positively phototropic thing

Answer 44

Plant shoots

Question 45

Give an example of a negatively phototropic thing

Answer 45

Plant roots

Question 46

What are positive phototropisms caused by

Answer 46

Caused by the plant hormones - auxins

Question 47

Where are auxins produced

Answer 47

In the tip of the shoot

Question 48

What happens with auxins

Answer 48

They cause cell elongation and move to the shady side of a plant to elongate cells to Point it to grow toward the light

Question 49

Who did experiments about auxins

Answer 49

Charles Darwin did experiment to see what was going on when plant shoots bend towards the Light So Frits warmolt went suggested how auxins worked with the extraction and purification of auxins

Question 50

Where other than tips of shoots are auxins found

Answer 50

Auxins are found in root tips where they have the opposite effect to that in the shoots

Question 51

Tell me about auxins in the roots

Answer 51

Auxins cause cells to stop elongating

Question 52

What's a positive gravitropism,

Answer 52

in roots, auxins cause cells to stop elongating and cause growth towards the direction of gravity This helps roots to anchor the plant in place to reach moisture underground

Question 53

What do gibberellins do

Answer 53

Help seeds to germinate and start to grow roots and shoots

Question 54

What's ethene gas

Answer 54

A plant hormone that helps fruit to ripen

Question 55

Tell me about selective weed killers

Answer 55

They contain artificial auxins to kill plants with broad leaves but not with narrow leaves Farmers can therefore kill weeds in wheat field without affecting the crop

Question 56

How can artificial auxins kill weeds

Answer 56

Can make some plants grow uncontrollably which can kill them

Question 57

Tell me about rooting powders

Answer 57

Auxins are also found in rooting powders which cause plant cutting to develop roots quickly Large numbers of identical plants can be produced quickly using cutting, compared to growing plants from seed

Question 58

Tell me about gibberellins

Answer 58

They are naturally released inside a Seed to start germination Some seeds need a period of darkness or cold before they can germinate but plant growers can use gibberellins to make there seeds germinate without this

Question 59

What's a photoperiodism

Answer 59

It's a response to an organism to the number of daylight hours in a day Some plants use this to flower at a certain time Flower growers can override photoperiodism by spraying plants with gibberellins

Question 60

How can gibberellins cause seedless fruits

Answer 60

Many plants only produce seeds after being pollinated which then allows egg cells to be fertilised and seeds to form Gibberellins can cause some plants to produce plants without this and give use seedless fruits Gibberellins can also be sprayed on some plants to make them bigger fruits

Question 61

Tell me some benefits of ethene

Answer 61

Can be used to ripen fruit after being transported and so not damaging them, Unripened fruit can be kept for longer in cold storage without going off Fruit producers often pick Unripened fruit and then ripen it using ethene Ethene makes sure a fruit reaches the shops in a Just ripened condition

Question 62

What is a stimulus

Answer 62

Change in environment that causes a response by an organism

Question 63

What's a tropism

Answer 63

Responding to a stimulus by growing towards or away from it

Question 64

What's a phototropism

Answer 64

A tropism towards the light is a positive phototropism A tropism away from the light are negatively phototropic

Question 65

Give an example of a positively phototropic thing

Answer 65

Plant shoots

Question 66

Give an example of a negatively phototropic thing

Answer 66

Plant roots

Question 67

What are positive phototropisms caused by

Answer 67

Caused by the plant hormones - auxins

Question 68

Where are auxins produced

Answer 68

In the tip of the shoot

Question 69

What happens with auxins

Answer 69

They cause cell elongation and move to the shady side of a plant to elongate cells to Point it to grow toward the light

Question 70

Who did experiments about auxins

Answer 70

Charles Darwin did experiment to see what was going on when plant shoots bend towards the Light So Frits warmolt went suggested how auxins worked with the extraction and purification of auxins

Question 71

Where other than tips of shoots are auxins found

Answer 71

Auxins are found in root tips where they have the opposite effect to that in the shoots

Question 72

Tell me about auxins in the roots

Answer 72

Auxins cause cells to stop elongating

Question 73

What's a positive gravitropism,

Answer 73

in roots, auxins cause cells to stop elongating and cause growth towards the direction of gravity This helps roots to anchor the plant in place to reach moisture underground

Question 74

What do gibberellins do

Answer 74

Help seeds to germinate and start to grow roots and shoots

Question 75

What's ethene gas

Answer 75

A plant hormone that helps fruit to ripen

Question 76

Tell me about selective weed killers

Answer 76

They contain artificial auxins to kill plants with broad leaves but not with narrow leaves Farmers can therefore kill weeds in wheat field without affecting the crop

Question 77

How can artificial auxins kill weeds

Answer 77

Can make some plants grow uncontrollably which can kill them

Question 78

Tell me about rooting powders

Answer 78

Auxins are also found in rooting powders which cause plant cutting to develop roots quickly Large numbers of identical plants can be produced quickly using cutting, compared to growing plants from seed

Question 79

Tell me about gibberellins

Answer 79

They are naturally released inside a Seed to start germination Some seeds need a period of darkness or cold before they can germinate but plant growers can use gibberellins to make there seeds germinate without this

Question 80

What's a photoperiodism

Answer 80

It's a response to an organism to the number of daylight hours in a day Some plants use this to flower at a certain time Flower growers can override photoperiodism by spraying plants with gibberellins

Question 81

How can gibberellins cause seedless fruits

Answer 81

Many plants only produce seeds after being pollinated which then allows egg cells to be fertilised and seeds to form Gibberellins can cause some plants to produce plants without this and give use seedless fruits Gibberellins can also be sprayed on some plants to make them bigger fruits

Question 82

Tell me some benefits of ethene

Answer 82

Can be used to ripen fruit after being transported and so not damaging them, Unripened fruit can be kept for longer in cold storage without going off Fruit producers often pick Unripened fruit and then ripen it using ethene Ethene makes sure a fruit reaches the shops in a Just ripened condition