Root physiology 2

Question 1

What is the primary cell wall made of in plants?

Answer 1

The primary cell wall exists in all cells and is made of cellulose, hemicellulose and pectin.​

Question 2

What helps plants from uprooting and overturning?

Answer 2

Resistance to uprooting:​
-root hairs​
-branching​
Resistance to overturning:​
-lignified roots​
-plate root system

Question 3

What is the secondary cell wall made up of and why?

Answer 3

​The secondary cell wall is formed after cell growth in specialised tissues. It contains cellulose, hemicellulose, pectin and lignin.
The lignin gives it a higher strength and rigidity than the primary wall and provides hydrophobicity (waterproof).​

Question 4

What are the factors that change soil nutritional content?

Answer 4

Dust, rain, floodwater, manure, fertilizers and pollutants.

Question 5

What is the difference between micro and macro nutrients?

Answer 5

macro means there are more of these nutrients within the plants and micro tends to mean traces.
Mineral nutrients are mostly available to plants as ions.

Question 6

Symbiosis with mycorrhizae​ (fungi)

Answer 6

Once roots have used all the nutrients near it, a fungi (Mycorrhizae) helps facilitate access to nutrients further away (PO4-) in exchange for carbohydrates.​ phosphate is not dissolved easily so harder for roots to absorb this.

Question 7

What are the two types of mycorrhizae

Answer 7

Ectomycorrhizal fungi: live outside the root cells​ (occur in 3% of land plants and only in trees in certain climates, temperate. grow mycelium network)
Endomycorrhizal: uses spores, develop within the root cortex cells. (80% of land plants, arbuscules within the roots, ).​

Question 8

What is the bacteria that aids in nitrogen fixation and how do plants repay the bacteria?​

Answer 8

fabaceae
Nodules host a symbiosis with rhizobia.​
Needs 16ATP to make 2NH3
Plants get fixed nitrogen while the rhizobia get carbohydrates and a sheltered environment.​
bacteroid is the form of the bacteria that can make the nitrogen fixation.
the plant makes leghemoglobin which is a way for the plant to transport oxygen to the bacteroid that is also needed for nitrogen fixation.

Question 9

What controls the amount of nitrogen ions in the soil?

Answer 9

plant controls the level of symbiosis

Question 10

What are plasmodesmata?

Answer 10

Plasmodesmata allow transport of macromolecules between adjacent cells. The desmotubule in the centre of the plasdesma connects the endoplasmic reticula.​

Question 11

What are the ways water and nutrients are transported to the xylem​

Answer 11

Apoplastic: through extracellular space ​
Symplastic: through cells, using plasmodesmata​
Transcellular: through cells, using transporters​

Whatever the pathway, nutrients and water rely on transporters to pass the Casparian strip. ​

Question 12

What maintains transportation throughout plants?
What are the secondary active carriers (transporters) against an electrochemical gradient called?

Answer 12

An electrochemical gradient

antiport
symport

Question 13

What are Haustorial roots

Answer 13

Haustorial roots attach to the host and drain nutrients from its vascular system.​

Question 14

What do storage roots store?

Answer 14

These store starch or water

Question 15

Types of roots that aren’t in the soil

Answer 15

Prop roots​- prevent overturning can grow from branches
velamen roots- these can photosynthesise (roots of orchids) special epidermis called velamen that is more waterproof than normal epidermis of roots to prevent water loss.