Module 3.3 Transplant In Plants

Question 1

Why do plants need a transport system

Answer 1

Plants are multicellular organism
They have a high metabolic rate
Plants have a small surface area to volume ration
Rate of diffusion would be slow because of large distance

Question 2

Can you draw the cross section of a vascular section in the root

Answer 2

Question 3

Can you draw cross section of vascular bundle in a stem

Answer 3

Question 4

Can you draw the cross section of a vascular bundle in a leaf

Answer 4

Question 5

What is the function of the xylem vessels

Answer 5

To transport water up the plant
Supports the plants (lignin)

Question 6

What the the function of the phloem

Answer 6

To transport assimilates from source to sink

Question 7

What features does the xylem have

Answer 7

It is hollow,
there are no end walls,
contains dead cells,
contains lignin,
has pits
Also has a ring or spiral structure for flexibility

Also has xylem parenchyma which stores food also contains tanin which prevents herbivores from eating the xylem

Question 8

State the function of lignin in the xylem and explain why it’s important

Answer 8

It also helps strength the cell

How?

prevents walls from collapsing when there is low turgor pressure.

Spiral band of lignin is flexible

Also helps reduce loss of water

Question 9

State the function of bordered pits

Answer 9

Reason

is to allow water to go out of the xylem

Why?

so tissues can be supplied with water.

Question 10

What substances are transported in the xylem vessel

Answer 10

Water and minerals

Question 11

What three parts of phloem tissue

Answer 11

Phloem paracheyma
Sieve tube elements
Companion cells

Question 12

What is the function of sieve tube elements

Answer 12

Living cells which form tube for transporting sugars.

They have holes which allow solutes to pass through

Question 13

What is the function of companion cells

Answer 13

Carry out living functions for themselves and sieve tube elements.

For example provide energy for active transport of solutes

Question 14

What is meant by the term source?

Answer 14

Where assimilâtes are loaded into to the phloem

Question 15

What is meant by the term sink

Answer 15

Where assimilates unload

Question 16

Exam Question

When a bark is removed from a tree, the phloem was removed. If a complete ring of bark is removed, the tree trunk will swell above the cut

Suggests two reason why

Answer 16

Sugar cannot pass where it’s been cut

So…

This decreases water potential and the water moves into the cells.

Another answer could be

The damage causes cell division, so it can produce cells to store sugar

Question 17

What is a dicotyledonous plant

Answer 17

A plant that has seeds made out of two parts

Question 18

What two ways can water move through the plant

Answer 18

Symplast
Apoplast

Question 19

Describe the apoplast pathway

Answer 19

At first the water goes through this pathway

• water is absorbed into cell wall
• travels through cortex (non living parts)
• via mass flow from high hydrostatic pressure to a low hydrostatic pressure

Question 20

Describe the symplast pathway

Answer 20

Through living parts of the cell

1. Water moves in through osmosis into the roots
2. Moves through the cytoplasm and plasdostomata

Question 21

Why do plants have a casparian strip

Answer 21

Forces water to move through plasma membrane
So what goes in is selected and others will be filtered out

Question 22

How does the water get loaded into the xylem

Answer 22

1- endodermis moves mineral ions into xylem first through active transport
2- this decreases wp in xylem
3- so water will move into xylem through osmosis down wp gradient
4- generates root pressure which pushes water up xylem

Question 23

Define transpiration

Answer 23

Loss of water vapour by evaporation through the stomata

Question 24

What are the benefits and the opposite of benefit of transpiration

Answer 24

1. Cools plant down
2. Causes a transpiration stream (movement of water and minerals ions up the stem)

Downside
1. May cause loss of water, which means less turgor pressure, so plant will wilt

Question 25

What factors affect transpiration

Answer 25

Temp Humidity Wind speed Light intensity

Question 26

How does temperature affect transpiration

Answer 26

The water molecules have more KE so they vibrate more, Makes it easier for water to evaporate from leaf Wp inside the leaf increases making water diffuse of leaf

Question 27

How does humidity affect transpiration

Answer 27

As humidity increases the rate of transpiration decreases More humid the more water vapour there in the air (the air is moister) Decreases wp gradient between leaf and air

Question 28

How does wind affect transpiration rate

Answer 28

Increases rate of transpiration Water molecules will be blown away from the stomata Increases water potential gradient So faster rate of transpiration

Question 29

How does light intensity affect the rate of transpiration

Answer 29

More stomata will open So greater photosynthesis More CO2 means more gas exchange happens So rate of transpiration increases

Question 30

What does a potomètre measure

Answer 30

Measures water uptake by plant by estimating transpiration rate

Question 31

How is water used up in plants

Answer 31

Turgor pressure Photosynthesis That’s why a potomètre is gives an estimation

Question 32

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Answer 32

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Question 33

Define translocation

Answer 33

Movement of assimilâtes from source to sink

Question 34

Why do plants use sucrose instead of glucose

Answer 34

Glucose can react Can change wp of cells Sucrose is big

Question 35

How does phloem loading work

Answer 35

1. H+ pumped out of companion cell through H+ pumps by active transport 2. Which increases H+ concentration is in outside cell 3. H+ wants to diffuse back into companion cell, so it’s gets co transported into Compnaian cell with sucrose 4. Sucrose diffuses from companion cell into sieve tube element 5. Which decreases wp inside sieve tube element 6. Water moves into sieve tube element by osmosis which generates turgor pressure for mass flow

Question 36

How does mass flow work

Answer 36

1. Water has a high turgor pressure at source 2. This flows down from source to sink down the pressure gradient

Question 37

How does phloem unloading work

Answer 37

1. Sucrose diffuses from phloem into sink 2. Sucrose moves into cells which maintains concentration gradient between cells and phloem 3. Loss of assimilates increases wp in the sieve tube element H20 moves into cells via osmosis or enters xylem

Question 38

What is a xérophytes

Answer 38

Plants like cacti which are adapted to live in dry environments So their adaptions prevent them from losing water

Question 39

Examples of xerophytes Cacti

Answer 39

Thick waxy cuticle: reduces water loss by evaporation Spines instead of leaves: reduces SA for water loss Close their stomata: during the hottest time of the day when transpiration rates are high Green stem: stem has lost of chlorophyll as cacti don’t have leaves Shallow widespread roots: take advantage of an water Fleshy stem: store water as they are ribbed so stem expands when there’s water

Question 40

Examples of xerophytes Marram grass

Answer 40

Sunken stomata in pits: sheltered from wind. Also can trap air in pits with help slow transpiration down Hairs on epidermis: traps air around stomata which reduces wp between leaf and air Roll up their leaves: in hot or windy conditions to trap air and to reduce SA Thick wavy cuticle: to prevent water loss from epidermis Dense spongy mesophyll: leaves fewer air spaces so less SA for diffusion Tap root: grow vertically specialised for food storage

Question 41

What is a hydrophyte

Answer 41

A plant that grows in water that need adaptions to cope with oxygen levels

Question 42

Hydrophytes adaptions Lillies,

Answer 42

Large flat leaves: contain air spaces which make them float, helps increase SA so they can absorb more sunlight Open stomata on upper epidermis: exposed for efficient gas exchange as it’s hard to get air in water Large air spaces: help plant float, act as store for oxygen, float on surface to obtain more light for photosynthesis Small roots: Roots needed for anchorage not to absorb minerals Thin or no wavy cuticle: don’t need them, they’re already in water