Leaves Module 6

Question 1

What are the primary functions of leaves?

Answer 1

Photosynthesis and gas exchange

Question 2

Photosynthesis

Answer 2

Occurs in the chloroplasts in the ground tissue
using light the plant converts water and co2 into carbs and oxygen
6 CO2 + 6H2O + energy = C6H12O6 + 6O2

Question 3

Gas exchange

Answer 3

occurs through the stomata of the dermal tissue
H2O is lost as vapor (transpiration)
CO2 is taken up for photosynthesis
O2 is emitted during ps and taken up at night

Question 4

Leaf modifications (7)

Answer 4

Climbing - tendrils in peas
Protections - stipules in cactus
Carnivorous - venus fly traps, pitcher plants
Food storage - onions, tulips
Bracts - poinsettias
Trichomes - hairs for protection
Propagation - maternity plant
Floating - water lily

Question 5

Leaf blade types

Answer 5

Simple and compund

Question 6

Leaf blade venation

Answer 6

Two main types are netted and parallel
venation is the fingerprint of the leaf
each vein ends services approximately 30 cells
netted usually in dicot
parallel usually in monocots

Question 7

4 Overall leaf shapes

Answer 7

obicular
ovate
obovate
lanceolate

Question 8

4 leaf base shapes

Answer 8

oblique
obtuse
cordate
peltate

Question 9

Shape of the leaf tip

Answer 9

acute
obtuse
retuse

Question 10

Leaf blade surface

Answer 10

smooth or rough
waxy
with or without hairs
hair type difference

Question 11

Leaf blade margins

Answer 11

serrate
serrulate
doubly serrate
crenate
dentate
undulate
sinulate

Question 12

Leaf petiole

Answer 12

attaches the leaf to the stem
stalk like portion of the leaf
some leaves have no petioles, called sessile

Question 13

Grass blade

Answer 13

sheath attaches at the node
ligules and auricles can be used to ID grass species
grass leaves do no have a petiole ie sessile

Question 14

Leaf stipules

Answer 14

outgrowths of the leaf
not present in all species so important in plant ID
blade like
protects the growing tip
usually falls off at maturity
sometimes presents as thorns
may turn into tendrils

Question 15

Leaf pattern arrangements

Answer 15

Alternate
Opposite
Whorled, more than two leaves per node

Question 16

Leaf dermal tissue

Answer 16

epidermis and stoma

Question 17

leaf epidermis

Answer 17

single layer of cells
cuticle is impermeable to water (waxy)
no chloroplasts
transparent
cuticle thickness is dependant on the environment

Question 18

leaf stoma

Answer 18

the pore through which gases exchange
represents 1% of leaf area, but lose a lot of water
distribution - all plant organs except for roots, most common in leaves, horizontal have more stomata on the bottom, vertical have even on both sides

Question 19

leaf ground tissue system

Answer 19

palisade mesophyll cells
spongy mesophyll cells
uniform mesophyll cells

Question 20

Palisade mesophyll cells

Answer 20

contains chloroplasts
specialize in light capture and photosynthesis
90% of the leafs photosynthesis is done here

Question 21

Spongy mesophyll cells

Answer 21

contains chloroplasts (10% of ps)
loosely arranged to facilitate gas exchange
separated by large intercellular spaces connected to stomatal cavities
air spaces can account for a large volume of the leaf

Question 22

Uniform mesophyll cells

Answer 22

appear in grasses with vertical leaves
light received from all directions in grass leaves

Question 23

Leaf vascular tissue system

Answer 23

conducting system for the leaf
consists of vascular bundles
parallel in monocots
netted in dicots

Question 24

Leaf structure adaptations

Answer 24

water storing leaves (xeromorphic)
floating (hydromorphic)
conifer
high vs low light