B1.2 Photosynthesis and Plants - Leaf Structure

Question 1

Mesophytic leaf

Answer 1

The leaf of a plant that is adapted to general conditions, such as those that are not too dry or too humid

Question 2

Epidermal tissue

Answer 2

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

Question 3

Waxy cuticle

Answer 3

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

Question 4

Palisade mesophyll

Answer 4

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 5

Chloroplasts

Answer 5

Sub-cellular structures that act as the site of photosynthesis, they contain a pigment called chlorophyll which is essential for photosynthesis

Question 6

Spongy mesophyll

Answer 6

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 7

Intercellular space

Answer 7

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

Question 8

Stomata

Answer 8

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

Question 9

Role of the stomata

Answer 9

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 10

Guard cells

Answer 10

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

Question 11

Activity of guard cells

Answer 11

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 12

Xylem

Answer 12

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 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