The Structure Of A Leaf

Question 1

Epidermal tissue

Answer 1

Tissue that covers and protects the plant, acts as a physical defence in plants, transparent to allow light through

Question 2

Waxy cuticle

Answer 2

A layer on the surface of the leaf which protects the plant and reduces water loss, thicker on the upper surface, transparent

Question 3

Palisade mesophyll

Answer 3

Photosynthetic tissue below the epidermis in a leaf, palisade cells are compacted together and contain high concentrations of chlorophyll and high quantities of chloroplasts for photosynthesis

Question 4

Spongy mesophyll

Answer 4

Layer of tissue found beneath the palisade mesophyll that is packed loosely for efficient gas exchange of carbon dioxide and oxygen, spongy mesophyll cells have increased surface areas for gas exchange

Question 5

Intercellular space

Answer 5

The space between cells, specifically the large amount of space between spongy mesophyll cells, provides room for an increased rate of diffusion

Question 6

Stomata

Answer 6

Small openings on the underside of a leaf through which oxygen, carbon dioxide and water can move

Question 7

Role of the stomata

Answer 7

The stomata opens to allow gas exchange where carbon dioxide can enter the plant for photosynthesis and excess oxygen from respiration leaves the plant, water is also lost from the plant here

Question 8

Guard cells

Answer 8

Pairs of cells that surround the stomata and control their opening and closing to optimise gas exchange and reduce water loss

Question 9

Activity of guard cells

Answer 9

Guard cells open the stomata in light conditions suitable for photosynthesis, guard cells close the stomata at night when photosynthesis cannot occur to reduce water loss

Question 10

Gas exchange in plants

Answer 10

Carbon dioxide diffuses into the plant in exchange for oxygen that diffuses out of the plant, this process is regulated by guard cells in the leaves that can open and close the stomata efficiently

Question 11

Xylem

Answer 11

Non-living vascular tissue that carries water and dissolved minerals from the roots of a plant to its leaves, the xylem is hollow and nearby cells are lignified or dead so water can move continuously

Question 12

Lignin

Answer 12

A chemical that provides support to xylem cells and prevents the unwanted movement of water into nearby cells

Question 13

Phloem

Answer 13

Living and elongated vascular tissue that carries sugar and organic substances throughout a plant, the phloem has sieve plates that act as pores to allow molecules to diffuse between cells

Question 14

Transpiration

Answer 14

The process of the movement of water through a plant and the loss of water from a plant through its leaves

Question 15

Rate of transpiration

Answer 15

The rate of water loss from a plant

Question 16

In hot and dry environments

Answer 16

Plants have waxy cuticles to reduce water loss and fewer stomata, they may also have thin needle-like leaves or spines to reduce water loss and to defend the plant, large surface area of roots that branch to reach water, large stems and reservoirs to store water

Question 17

In humid environments such as rainforests

Answer 17

Plants have broad leaves to optimise exposure to light in shaded environments for photosynthesis, waxy surface that rain can run off to prevent damage, many stomata to allow sufficient transpiration and gas exchange

Question 18

Marram grass

Answer 18

A type of grass that is adapted to windy, exposed conditions, it can fold up its leaf structure to reduce water loss in dry conditions

Question 19

Aquatic plants such as water lilies

Answer 19

Have stomata on the upper surface of the leaf to allow gas exchange with the air, increased water loss as water does not need to be conserved