Leaf as an example of a plant organ Flashcards
1
Q
Organs
A
- groups of tissues
- perform specialised functions
2
Q
Main angiosperm plant organs
A
- roots
- stems
- leaves
- flowers
- fruit
3
Q
Root - primary function
A
- anchor plants
- absorb water and minerals
4
Q
Stem - primary function
A
Support leaves, flowers and fruit
Provides a pathway for food and water e.g. from root to leaf
5
Q
Leaf - primary function
A
- Photosynthesis
- Transpiration
- Gaseous exchange
6
Q
Flower - primary function
A
Reproduction through pollination
7
Q
Fruit - primary function
A
- Protect seed
- Help disperse seed
8
Q
Leaves where both surfaces look the same
A
Isobilateral
9
Q
Leaves where both surfaces different
A
Dorsiventral
10
Q
Leaf cuticle
A
- Waxy surface layer
- Prevents unwanted water loss
- Protects against infection
11
Q
Leaf epidermis
A
- Outer cell layer of leaf
- Protects
- Prevents unwanted water loss
12
Q
Palisade parenchyma
A
- Cells closely packed on dorsal side
- Mainly for photosynthesis
- Slightly elongated with lots of chloroplasts
13
Q
Transport system in leaf
A
- Vascular system
- xylem for water and minerals
- phloem for sugars
14
Q
Ventral leaf surface consists of…
A
- Epidemis - protect
- Stoma - pores allowing gases in and out of leaf
15
Q
Spongy mesophyl
A
- Chlorenchyma loosely packed with lots of air spaces
- Gas exchange and some photosynthesis
16
Q
Guard cells
A
- two per stoma
- can open and close stoma
- regulate and control water loss and gas exchange
17
Q
Movement of carbon dioxide in the leaf
A
- 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)
18
Q
Movement of water in the leaf
A
- 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)
19
Q
Movement of sugars in the leaf
A
- 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
20
Q
Movement of oxygen in the leaf
A
- Slowly through epidermis by diffusion
- quickly through leaf in intercellular air spaces and stoma by diffusion
- excess produced by photosynthesis
- required for cellular respiration
21
Q
When do a leafs stoma usually open up and close?
A
- 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)
