Gallery of diagram

 

Mind map (summary of topic)

 

MCQ

 

Lets answer the question below. Enjoy :)

1. Vascular tissue that transports water and mineral upwards from a plant's roots is known as ____________.

a. Chlorophyll

b. Stomata

c. Xylem 

d. Phloem

2. Plants absorbs water through the ___________. 

a. stem

b. roots

c. leaves

d. all above 

3. How do water enter the roots from soil?

a. Diffusion 

b. Osmosis

c. Transpiration

d. Active transport

4. Water vapor exits a plant leaf by __________.

a. the palisade cells

b. the stomata

c. the spongy mesophyll

d. the epidermis

5. Transpiration is _______________.

a. The movement of water through a plant from the roots up the stem

b. The flow of water into plant roots by osmosis from the soil

c. The process of minerals and sugars moving through plant veins

d. The loss of water from the leaves of a plant by the process evaporation

6. Why is the evaporation of water from leaves is important?

a. It makes the plant wilt

b. It cools leaves and helps move water up the plant

c. It helps the plant to respire

7. Where is xylem found in the plant?

a. leave - roots - stems

b. roots - stem - leaves 

c. root hairs - leaves - veins 

d. stem - roots 

Transpiration & Factor affecting transpiration

 Transpiration - loss water vapor from the plant. 

• Water is continuously evaporating from the surface of leaf cells exposed to air. 
• Water exits the leaves through openings in the leaves through stomata.

Factors affecting transpiration:

1. Temperature 

2. Wind speed and humidity 

3. Air currents 

4. Carbon dioxide

5. Soil water availability

Root pressure

• Root pressure occurs when the roots continue to take in mineral and the rate of transpiration is low.  

• This process is produced by osmotic pressure in the cells of the root.
•  Root pressure common during spring seasons before the leaves develop and rate of transpiration is rapid. 
• Thus, water is forced from the high pressure (in roots) to low pressure (in leaves). 

The upward movement of water in plants

• Water transport occurs in a plant's xylem tissue & moves upward through a plant through xylem tissue.
• The fluid mixture of materials flowing through the xylem is called sap.  

• Diffusion, transpiration and capillary action must occur together in order to move the upward through plant.

1. Diffusion 

• Plant roots absorb water from the soil through diffusion or osmosis.
• The roots (higher salt concentration). The water flows from the low salt side to the high salt side to the concentration equal.
• The membrane is semi-permeable but if the salt concentration inside the root becomes too low, it will actively transport salt into roots. 

2. Capillary action

• Water molecules have a strong attraction to each other causing the molecules to stick together.
• They also adhere to the surface of the xylem.
• As the plant transpires, water molecule evaporates, pulling another water molecule up through the xylem.
• The water sticks to the side of the xylem and not fall back down.

Cohesion force: The ability of molecules of the same kind to stick together. Water molecules are polar, having positive and negative sides, which causes their cohesion.

Adhesion force: The tendency of molecules different kinds to stick together. Water sticks to the cellulose molecule in the walls of xylem, the force gravity give rise of water within xylem.

3. Transpiration 

• Plants lose water through the leaf surface and stomata involves transpiration.
• Plants lose water through the leaf surface from the stomata or pores in the leaf surface used for respiration and photosynthesis. 

Water transport in plants

 Transport systems are found in the vascular plants. Two types of vascular tissue:

• Xylem = transports water and minerals in the plants
• Phloem = transport food materials; synthesized by the leaves during photosynthesis and hormones.

Transport of water and minerals in plant 

The path taken is : soil - roots - stems - leaves 

Most plants secure the water & minerals from their roots. The minerals (e.g., K+ , Ca+) travel dissolved in the water. 

Water & dissolve mineral nutrients enter the plant via 2 routes 

• water & mineral nutrients enter the plant via 2 routes

1. Symplast: it crosses the plasma membrane and then passes from cell to cell through plasmodesmata.
2. Apolast: in the spaces between the cells and in the cells walls themselves. This water has not crossed a plasma membrane. 
   

Pathway of water into roots 

• Access water to the apoplast: Uptake of soil solution (water + minerals) of root hairs.
• Access water to the symplast: Water + minerals across the plasma membrane of root hairs.
• Water and minerals move along the apoplast and transported into the protoplast of epidermis cells, then cortex cells and move inward via the symplast.