Plant organs

Question 1

What are 2 functions of roots?

Answer 1

Anchorage- hold plant firm in soil

absorption- absorb water and mineral salts from soil

Question 2

What root system is in dicot plants?

Answer 2

Tap root system

Question 3

External structure of root? (5)

Answer 3

mature region- lateral branches=further absorption and anchorage
root hair region- epidermal outgrowths=max absorption
region of elongation- new cells elongate
meristematic region- meristematic tissue= form new cells
root cap- surrounds and protect growing point

Question 4

Internal structure of root and functions? (11)

Answer 4

Root hairs- increase surface area for absorption
epidermis- protect underlying tissue(no cuticle)
exodermis

Cortex:

• Parenchyma- transport water+ dissolved substances to xylem and stores starch
• endodermis: regulates water passage through Caspary bands

Vascular stele

• xylem
• phloem
• cambium- secondary growth
• pericycle- meristematic for lateral roots etc…

Question 5

How to identify root?(4)

Answer 5

• cross shaped xylem
• phloem between xylem arms
• Defined endodermis
• Root hairs present

Question 6

What is the main function of leaves?

Answer 6

photosynthesis- trap radiant energy through chloroplasts. combine h20 from vascular bundles and co2 from stoma to release glucose stored as starch and oxygen released via stoma.

Question 7

Functions of Stem?(5)

Answer 7

• bears leaves in favorable position for photosynthesis
• bears fruits in favorable position for seed distribution
• bears flowers in favorable position for pollination
• transports organic substances from leaves to rest of plant
• transports water and mineral salts from roots to rest of plant

Question 8

External structure of stem?(4)

Answer 8

• node
• internode
• axillary bud(lateral growth)
• terminal bud(primary growth)

Question 9

Internal structure of stem and functions? (12)

Answer 9

epidermis- protect underlying tissue and cuticle to prevent water loss

Cortex:
Collenchyma (hypodermis)- strengthen and support plant
Parenchyma- Intracellular air spaces for gaseous exchange and stores organic substances
Endodermis- stores starch

vascular bundle:

• xylem
• phloem
• cambium-meristematic=secondary growth
• sclerenchyma cap- protect and surround vascular bundle

medullary ray- transports substances from medulla and cortex
medulla

Question 10

Internal structure of leaves? (17)

Answer 10

cuticle
epidermis

Mesophyll:

• palisade parenchyma
• chloroplasts
• spongy parenchyma
• intracellular air spaces

Vascular bundle(vein):

• Bundle sheath
• xylem
• cambium
• phloem

Stomata:

• Guard cells
• stoma
• air chamber

lower epidermis

Question 11

Adaptations of leaves to functions?(7)

Answer 11

1. flat broad lamina: increase surface to sun
2. thin lamina: easy Gas exchange diffusion
3. cuticle impermeable and transparent: prevent moisture loss and allow sunlight penetrate
4. Many stoma lower epidermis= gas exchange
5. epidermis transparent= allow sunlight
6. Palisade mesophyll:
   - thin cell wall: osmosis diffusion
   - no Intracellular air spaces/ longitudinal/below epidermis= max surface to sun
   - many chloroplasts rotate= max surface to sun
7. Spongy mesophyll
   - thin cell wall: osmosis diffusion
   - Intracellular air spaces= gas exchange
   - chloroplasts= sunlight absorption

Question 12

How to identify dicot stem?(3)

Answer 12

• xylem and phloem in vascular bundles
• medulla present
• Vascular bundles in circle

Question 13

What are annual rings?

Answer 13

New ring of secondary xylem formed every year

Question 14

What is dicot stem with cambium called?

Answer 14

Open vascular bundle

Question 15

External structure of leaf?(10)

Answer 15

1-lamina
2-base
3-axil
4-axillary bud
5-stem
6-node
7-veins
8-margin
9-apex
10-petiole