CH4

Question 1

Structure of Xylem

Answer 1

Xylem vessels:
Dead cells with no cytoplasm
hollow vessels
Walls of xylem vessels have uneven lignin thickening

Tracheid:
pointed end

Question 2

structure of Phloem

Answer 2

Sieve tube:
do not have nuclei/ribosome/vacuole to allow passing through of sucrose
has sieve plate with pores; allow flow of organic compounds

Companion cells:
Has many mitochondria to produce atp molecules
allow transport of sucrose from leave to sieve tube via active transport

Question 3

Process of transport of water and mineral salts from water to leaves

Answer 3

Root Pressure
-Soil water is hypotonic to cell sap of root hair cells because mineral salts is actively pumped by root hair cells into vacuole
-water from soil diffuse into root hair cell and epidermal cell via osmosis
-Water diffuses from root hair cell into cortex by osmosis due to high water potential of root hair cells
_Root pressure produced push water into xylem vessel of roots and into xylem vessels of stem

Capillary Action
-Root pressure cannot transport water to the leaves for tall plants
-Capillary action produced by adhesion forces and cohesion forces help the movement of water molecules in xylem vessels
-Produces a pulling force which continuously moves water in xylem vessels

Transpirational Pull
-When transpiration occur, water diffuses out as water vapour from spaces between cells to the surrounding through opened stoma
-Spongy mesophyll cells have lower water potential than adjacent cells, so water diffuses into spongy mesophyll from adjacent cells through osmosis
-Continuous loss of water through stoma by transpiration produces a suction force that pulls water from xylem vessels of leaf to outside of the leaves called transpirational pull

Question 4

Process of guttation & its Similarity with Transpiration

Answer 4

Happens at night and early morning
Water loss in the form of water droplets
Only occur in herbacous plant
Occur through hydathodes
Water released is rich in minerals and organic substances
Happen when root pressure is high
Do not give cooling effect
Occur when light intensity & temperature is low

Similarity with Transpiration
Occur through leaves
Causes water loss from plants
help transport water and mineral salts in plant

Question 5

Effects of no guttation on plants

Answer 5

Effective root pressure cannot be maintained
Waste substances cannot be eliminated
leaf vein burst as leaf vein pressure becomes high
water absorption is distrupted

Question 6

Effects of no transpiration

Answer 6

Optimum temperature of plant cannot be maintained; disrupt biochemical reaction and denature enzyme
Mineral ions cannot be transported from root to leave
Water cannot be transported from root to leaves causes plants to wilt

Question 7

Process of translocation

Answer 7

Sucrose is actively transported to the sieve tubes
Water potential in the sieve tube becomes low so water diffuse from xylem into sieve tube via osmosis
hydrostatic pressure in sieve tube becomes high
Phloem sap is pushed along the sieve tube to other organs of the plant
Sucrose is transported from sieve tube to other parts (shoots roots stem fruit tubers) by active transport
Water diffuses into xylem by osmosis due to high water potential in sieve tube

Question 8

3 Plants suitable for phytoremediation

Answer 8

Sunflower; act as hyperaccumulator to eliminate heavy metals and radioactive substance

Water cabbage; fast growth rate & eliminate heavy metals

water spinach; absorb heavy metals