Plant organs and transport in plants

Question 1

Where is meristem tissue found?

Answer 1

At the growing tips of shoots and roots

Question 2

waxy cuticle

Answer 2

• Protective layer on top of leaf, prevents water from evaporating

Question 3

Upper epidermis

Answer 3

• Thin and transparent to allow light to enter the palisade mesophyll layer underneath it.

Question 4

Palisade mesophyll

Answer 4

Column shaped cells tightly packed with chloroplasts to absorb more light, maximising photosynthesis

Question 5

Spongy mesophyll

Answer 5

contains internal air spaces that increases the surface area to volume ratio for the diffusion of gases (mainly carbon dioxide).

Question 6

Lower epidermis

Answer 6

contains guard cells and stomata

Question 7

Guard cell

Answer 7

Absorbs and loses water to open and close the stomata to allow carbon dioxide to diffuse in, oxygen to diffuse out

Question 8

stomata

Answer 8

Where gas exchange takes place. It opens during the day; closes during the night. Evaporation of water also takes place from here. In most plants, found in much greater concentration on the underside of the leaf to reduce water loss.

Question 9

Vascular bundle

Answer 9

Contains xylem and phloem to transport substances to and from the leaf

Question 10

xylem

Answer 10

Transports water into the leaf for mesophyll cells to use in photosynthesis and transpiration from stomata.

Question 11

Phloem

Answer 11

Transports sucrose and amino acids around the plant

Question 12

Palisade mesophyll tissue is made from

Answer 12

palisade mesophyll cells

Question 13

Feature- Large surface area- adaptation of leaves

Answer 13

• Increases surface area for diffusion of carbon dioxide and absorption of light for photosynthesis

Question 14

Feature- thin

Answer 14

Allows carbon dioxide to diffuse to the palisade mesophyll cells quickly

Question 15

chlorophyll

Answer 15

Absorbs light energy so that photosynthesis can take place

Question 16

Feature-network of veins

Answer 16

• Allows the transport of water to the cells of the leaf and carbohydrates from the leaf for photosynthesis (water for photosynthesis, carbohydrates as a product of photosynthesis)

Question 17

Feature- stomata

Answer 17

• Allows carbon dioxide to diffuse into the leaf and oxygen to diffuse out

Question 18

Feature- epidermis is thin and transparent

Answer 18

• Allows more light to reach the palisade cells

Question 19

Feature- thin cuticle made of wax

Answer 19

• To protect the leaf without blocking sunlight

Question 20

Feature- palisade cell layer at the top of the leaf

Answer 20

• Maximises the absorption of light as it will hit chloroplasts in the cell directly

Question 21

Feature- spongy layer

Answer 21

-Air spaces allow carbon dioxide to diffuse through the leaf, increasing the surface area

Question 22

Feature- vascular bundles

Answer 22

• Thick cell walls of the tissue in the bundles help to support the stem and leaf.

Question 23

Pathway of CO2 molecule when leaf is photosynthesising

Answer 23

1, Higher concentration of CO2 in the atmosphere compared to inside the leaf
2, CO2 diffuses into leaf through open stoma into air space in spongy mesophyll
3, CO2 diffuses through cell wall and cell membrane of mesophyll cell, dissolves in cytoplasm and diffuses into chloroplast.

Question 24

The structure of a leaf enables

Answer 24

air to circulate within it to maximise the diffusion of carbon dioxide to the chloroplasts for photosynthesis

Question 25

The structure of a leaf enables

Answer 25

air to circulate within it to maximise the diffusion of carbon dioxide to the chloroplasts for photosynthesis

Question 26

What two types of transport vessel to plants contain?

Answer 26

xylem and phloem

Question 27

xylem vessels

Answer 27

• transport water and minerals (pronounced: zi-lem) from the roots to the stem and leaves
• It is composed of hollow tubes strengthened by lignin adapted for the transport of water in the transpiration stream

Question 28

Phloem vessels

Answer 28

• transport food materials (mainly sucrose and amino acids) made by the plant from photosynthesising leaves to non-photosynthesising regions in the roots and stem (pronounced: flow-em)
• (xylem and phloem)These vessels are arranged throughout the root, stem and leaves in groups called vascular bundles

Question 29

Root hair cells adaptations

Answer 29

• Root hairs are single-celled extensions of epidermis cells in the root which increase the surface area of the cells significantly; this increases the rate of the absorption of water by osmosis and mineral ions by active transport
• They grow between soil particles and absorb water and minerals from the soil

Question 30

Pathway of water

Answer 30

• Water enters the root hair cells by osmosis
• This happens because soil water has a higher water potential than the cytoplasm of the root hair cell
• Osmosis causes water to pass into the root hair cells, through the root cortex and into the xylem vessels
• Once the water gets into the xylem, it is carried up to the leaves where it enters mesophyll cells

Question 31

Transpiration definition

Answer 31

Transpiration is defined as the loss of water vapour from plant leaves by evaporation of water at the surfaces of the mesophyll cells followed by diffusion of water vapour through the stomata

Question 32

How does a plant replace the water that has been lost due to transpiration?

Answer 32

Water travels up xylem from the roots into the leaves of the plant to replace the water that has been lost due to transpiration

Question 33

How is the xylem adapted?

Answer 33

• A substance called lignin is deposited in the cell walls which causes the xylem cells to die
• These cells then become hollow (as they lose all their organelles and cytoplasm) and join end-to-end to form a continuous tube for water and mineral ions to travel through from the roots
• Lignin strengthens the plant to help it withstand the pressure of the water movement

Question 34

Movement in the xylem

Answer 34

It takes place in one direction-from the roots to the leaves

Question 35

The xylem contains

Answer 35

a continuous column of water

Question 36

What has an effect on the rate at which transpiration occurs?

Answer 36

• air movement
• humidity
• temperature
• light intensity

Question 37

Air movement- high

Answer 37

-More transpiration- good airflow removes water vapour surrounding the leaf which presents a concentration gradient between the leaf and the air, increasing water loss.

Question 38

Humidity- high

Answer 38

-Less transpiration because humidity is a measure of moisture (water vapour) in the air; when the air is saturated with water vapour, the concentration gradient is weaker so less water is lost.

Question 39

Light intensity -high

Answer 39

-More transpiration because guard cells are responsive to light intensity;when it is high they are turgid and the stomata open allowing water to be lost.

Question 40

Temperature high

Answer 40

-More transpiration because at higher temperatures, particles have more kinetic energy so transpiration occurs at a faster rate as water molecules evaporate from the mesophyll and diffuse away faster than at lower temperatures.

Question 41

Transpiration:stomata

Answer 41

-Stomata can be opened or closed depending on the conditions the plant is in; this activity is controlled by guard cells
-The role of stomata and guard cells (found predominantly on the underside of the leaf) is to control gas exchange and water loss
-Guard cells have cell walls with unevenly distributed cellulose – the inner wall is thicker and the outer wall is thinner to aid opening and closing of the stomata
-When the availability of water is high, guard cells become turgid as a result of osmosis
When guard cells are turgid, the stomata they surround are open and air can circulate in from the environment but water is consequently lost via transpiration
-When less water is available, the guard cells lose water by osmosis and become flaccid
-When guard cells are flaccid, they pull together, closing the stomata and reducing water loss via transpiration
-Stomata are predominantly distributed on the underside of the leaf where it is cooler and shaded (lower light intensity) – this leads to less transpiration and therefore less water loss

Question 42

Aphids get

Answer 42

sugars/sucrose from the plant

Question 43

PHloem and xylem differences

Answer 43

Phloem
-they transport soluble food particles throughout the plant
-two-directional flow
-translocation
-living (engage in mitosis)
Xylem
-xylem vessels transport water molecules and mineral ions from the root system through the stem and to the leaf. 
-one directional flow
-(non-living)

Question 44

if guard cell is turgid

Answer 44

stomata opens

Question 45

If guard cell is flaccid

Answer 45

stomata closes