Leaf as an example of a plant organ

Question 1

Organs

Answer 1

• groups of tissues
• perform specialised functions

Question 2

Main angiosperm plant organs

Answer 2

• roots
• stems
• leaves
• flowers
• fruit

Question 3

Root - primary function

Answer 3

• anchor plants
• absorb water and minerals

Question 4

Stem - primary function

Answer 4

Support leaves, flowers and fruit

Provides a pathway for food and water e.g. from root to leaf

Question 5

Leaf - primary function

Answer 5

• Photosynthesis
• Transpiration
• Gaseous exchange

Question 6

Flower - primary function

Answer 6

Reproduction through pollination

Question 7

Fruit - primary function

Answer 7

• Protect seed
• Help disperse seed

Question 8

Leaves where both surfaces look the same

Answer 8

Isobilateral

Question 9

Leaves where both surfaces different

Answer 9

Dorsiventral

Question 10

Leaf cuticle

Answer 10

• Waxy surface layer
• Prevents unwanted water loss
• Protects against infection

Question 11

Leaf epidermis

Answer 11

• Outer cell layer of leaf
• Protects
• Prevents unwanted water loss

Question 12

Palisade parenchyma

Answer 12

• Cells closely packed on dorsal side
• Mainly for photosynthesis
• Slightly elongated with lots of chloroplasts

Question 13

Transport system in leaf

Answer 13

• Vascular system
• xylem for water and minerals
• phloem for sugars

Question 14

Ventral leaf surface consists of…

Answer 14

• Epidemis - protect
• Stoma - pores allowing gases in and out of leaf

Question 15

Spongy mesophyl

Answer 15

• Chlorenchyma loosely packed with lots of air spaces
• Gas exchange and some photosynthesis

Question 16

Guard cells

Answer 16

• two per stoma
• can open and close stoma
• regulate and control water loss and gas exchange

Question 17

Movement of carbon dioxide in the leaf

Answer 17

• Made during cellular respiration
• Excess exits the leaf into atmosphere esp. at night
• Required for photosynthesis esp. in the day
• Movement by diffusion through stoma (and some through epidermis)

Question 18

Movement of water in the leaf

Answer 18

• Comes from xylem in vascular bundles (diffusion)
• Moves between cells (diffusion through intercellular spaces)
• Moves into cells (osmosis across membrane)
• Moves out stoma (diffusion into atmosphere)

Question 19

Movement of sugars in the leaf

Answer 19

• Glucose made by photosynthesis in the day
• Dissolves in water
• Moves in solution out of cell into phloem in vascular bundle
• Transported to other parts of plant where needed
• If excess sugar then starch stored in chloroplasts in day
• Starch used up at night

Question 20

Movement of oxygen in the leaf

Answer 20

• Slowly through epidermis by diffusion
• quickly through leaf in intercellular air spaces and stoma by diffusion
• excess produced by photosynthesis
• required for cellular respiration

Question 21

When do a leafs stoma usually open up and close?

Answer 21

• Open when light strikes leaf in morning
• Close during night, too hot (midday)
• Closed and when water uptake reduced (to reduce transpiration and water loss)