Organisation - Plant tissues, organs and systems

Question 1

what is the epidermal tissue

Answer 1

tissue which covers the whole plant and protect the surface of the leaf

Question 2

examples of plant organs

Answer 2

stems , root , leaves, reproductive structures

Question 3

what is the palisade mesophyll tissue

Answer 3

part of the leaf where most photosynthesis happens

Question 4

what is the spongy mesophyll tissue

Answer 4

part of the leaf that has big air spaces to allow gases to pass through

• The air spaces allow carbon dioxide to diffuse from the stomata ,through the spongy mesophyll to the palisade cell

Question 5

what are the xylem and phloem for

Answer 5

transporting things like water, food and mineral ions around the plant

Question 6

what is the meristem tissue

Answer 6

found at the growing tips of shoots and roots and is able to differentiate into lots of different types of plant call, allowing the plant to grown

Question 7

how is the epidermal tissues specialised to do its job

Answer 7

covered with a waxy cuticle which helps to reduce water loss toprevent the leaf from drying out

Question 8

how is the upper epidermis specialised to do its job

Answer 8

transparent so that light can pass through it to the palisade layer

Question 9

how is the palisade layer specialised to do its job

Answer 9

has lots of chloroplasts so they can capture the most light

Question 10

how does translocation work

Answer 10

• phloem is made up of columns of elongated living cells with small pores in the end walls to allow cell sap to flow through
• transport food substances made in the leaves to the rest of the plant for immediate use or storage
• transport goes in both directions, this is translocation

Question 11

How does the transpiration stream work

Answer 11

• xylem made of dead cells joined end to end with no end walls
• they carry water and mineral ions from the roots to the stems and leaves
• the transpiration stream is the movement of water from the roots, through the xylem and out of the leaves

Question 12

Explain the transpiration stream

Answer 12

Transpiration starts with the evaporation of water from cells inside the leaf.

The water vapour, then diffuses through the air spaces in the spongy mesophyll and out of the leaf through the stomata

Then water passes from the xylem into the leaf to replace the water that has been lost

Finally, water is drawn into the root hair cell and up the xylem vessels into the leaf

Question 13

how is the lower epidermis specialised to do its job

Answer 13

full of little holes called stomata, which let CO2 diffuse directly into the leaf

Question 14

how does light intensity affect transpiration rate

Answer 14

• brighter light, greater rate of transpiration
• this is because as it gets darker, the stomata starts to close and photosynthesis can’t happen in the dark
• when the stomata is closed, very little water can escape
• The rate of photosynthesis increases so the stomata open to allow the carbon dioxide in and allow water vapour to leave

Question 15

how does temperature affect transpiration rate

Answer 15

warmer, faster rate of transpiration

• this is because when its warm, evaporation is faster

Question 16

how does air flow affect the rate of transpiration

Answer 16

the better the air flow ( strong wind ) the faster the transpiration rate

• this is because when there is good air flow, water vapour is swept away, maintaining a low concentration of water in the air outside the leaf, diffusion then happens quicker

Question 17

how does humidity affect the transpiration rate

Answer 17

the drier the air around a leaf , the faster transpiration happens

• this is because if the air is humid, there’s a lot of water in it already, so theres not much of a difference between the inside and outside of the leaf, and diffusion happens fastest when one area is more concentrated than the other

Question 18

how are guard cells adapted for their job

Answer 18

• job is to open and close the stomata and for gas exchange and controlling water loss on a leaf
• thin outer walls and thickened inner walls make the opening and closing work
• When there is a high light intensity, they swell up, causing them to open so co2 can diffuse into the leaf and be used in photosynthesis
• In hot conditions, the plant closes its stomata to reduce water loss by transpiration, meaning that the plants can no longer photosynthesise

Question 19

where do you usually find stomata

Answer 19

in the lower epidermis

Question 20

What is the function of the stomata

Answer 20

allow carbon dioxide to enter the leaf and oxygen to leave
- They also help control the amount of water vapour that can pass out of the leaf

Question 21

difference between xylem and phloem vessels

Answer 21

phloem is bidirectional whilst xylem travels only in one direction

phloem transports food used in photosynthesis and xylem transports water and minerals

Question 22

describe the transport of water through a plant from the roots to the atmosphere

Answer 22

• xylem carries water from roots to stem and leaves
• the water evaporates from the leaves through the stomata

Question 23

what is transpiration

Answer 23

the loss of water from the surface of leaves

Question 24

what is transpiration caused by

Answer 24

the evaporation and diffusion of water from a plants surface

Question 25

describe the structure of a xylem

Answer 25

• made up of dead cells joined end to end with no end walls between them for continuous flow of water
• they are strengthened with a material called lignin
• they carry water and mineral ions from the roots to the stems and leaves (one direction)

Question 26

describe the structure of a phloem cell

Answer 26

• made up of columns of long living cells with small pores in the end walls to allow cell sap to flow through
• They transport food substances (mainly dissolved sugars) made in the leaves to the rest of the plant for immediate use or for storage
• transport is bidirectional

Question 27

why do stomata close as it begins to get darker

Answer 27

because photosynthesis cannot happen in the dark, so they dont need to be open to let CO2 in, very little water can escape when stomata is closed

Question 28

why would you find more stomata on the undersides of leaves rather than the top

Answer 28

because the lower surface is shaded and cooler, meaning less water is lost through the stomata than if they were on the top

Question 29

what happens when there is a lot of water in a plant

Answer 29

when the plants have a lot of water, the guard cells fill with it and go plump and turgid, making the stomata open so gases can be exchanged for photosynthesis

Question 30

what happens when there is a lack of water in a plant

Answer 30

• when the plants short of water, the cells lose water and become flaccid, making the stomata close, this helps stop too much water vapour escaping

Question 31

What is the function of the xylem?

Answer 31

It transports water from the roots to the stems and the leaves

-Xylem also transports dissolved mineral ions. these include magnesium, which is used to make chlorophyll

Question 32

What is the function of the phloem?

Answer 32

• phloem tissue transports dissolved sugars produced by photosynthesis from the leaves to the rest of the plant
• The sugars that are produced can be stored as starch or can be used for respiration

Question 33

What is translocation?

Answer 33

The movement of sugars and other molecules through the phloem tissue

Question 34

How does water enter the roots of plants?

Answer 34

through the root hair cells

Question 35

Why is transpiration important?

Answer 35

Because it brings water to the leaves and water is required for photosynthesis

• The transpiration stream transport dissolved mineral ions, such as magnesium, which play important roles in the plant
• The evaporation of water from the leaves cools the leaves down, especially in warm weather

Question 36

why are stomata on the underside of the leaf

Answer 36

to reduce water loss by transpiration.