- the main constituents of a plant body (i.e. % water, % carbohydrates, etc.)
80-90% is water 96% carbohydrates such as cellulose
- What are the most abundant elements in dried plant biomass?
Carbon, oxygen and hydrogen
WHAT IS THE MEANING OF ESSENTIAL ELEMENT
A chemical element is considered an essential element only if it is required for a plant to complete its life cycle and produce another generation.
WHAT IS THE MEANING OF MACRONUTRIENT
NUTRIENTS THAT ARE NEEDED BY PLANTS IN LARGE AMOUNTS THERE ARE 9
carbon, oxygen, hydrogen, nitrogen, phosphorus and sulfur, potassium, magnesium AND CALCIUM
WHAT IS THE MEANING OF MICRONUTRIENT
NUTRIENT THAT IS REQUIRED IN TRACE AMOUNTS
what is meant by a mutualistic relationship
Mutually beneficial relationship between plants and soil bacteria or fungi
WHAT IS RIZOSPHERE?
the soil layer that surrounds the plant’s roots.
WHAT ARE the benefits to plants from their association with bacteria
Enhance plant growth by producing chemicals that stimulate plant growth others produce antibiotics that protect roots from disease. & Make nutrients more available to roots or absorb toxic metals. Increase crop yield and reduce fertilizers and pesticides.
WHAT ARE the benefit to bacteria from their association with plants.
Nutrients secreted by roots supply the energy in the rhizosphere so bacterial adaptations that help a plant thrive also help the bacteria
WHAT DOES THE Ammonifying bacteria DO
When a plant or animal dies and expels waste the intitial form of nitrogen is organic.
convert the organic nitrogen within the remains back to ammonium (NH4+) a process called ammonification
WHAT DOES Nitrogen-fixing bacteria DO?
convert gaseous nitrogen (N2) TO NH3, WHICH IN TURN PICKS UP another H+ in the soil solution to form NH4+
WHAT DOES Nitrifying bacteria DO?
– after the roots absorb nitrate (NO3-) a plant enzyme reduces it back to NH4+, which other enzymes incorporate into amino acids and other organic compounds.
WHAT ARE The benefits to mycorrhizae from their association with plants.
The plants supply the fungi with organic nutrients such as carbohygrates
WHAT ARE The benefits to plants from their association with mycorrhizae.
Improve delivery of phosphate ions and other minerals to plants because the vast mycelia networks of fungi are more efficient that the plant’s roots at acquiring these minerals from the soil.
WHAT IS the role of the xylem in the transport of water and minerals.
They transport the water and minerals by bulk flow upward into the shoot system
WHAT IS the importance of root hairs in the absorption of water and minerals.
The root hairs absorb the soil solution, which consists of water molecules and dissolved mineral ions that are not bound tightly to soil particles.
See Fig. 29.4 (pg. 574) and know the difference between the apoplastic and symplastic movement.
HOW DOES THE epidermis control the movement along the symplastic route.
Epidermis is the innermost layer of the cortex, functions as a last checkpoint for the selective passage of minerals into the vascular cylinder.
How does the Casparian strip and the epidermis control the movement along the apoplastic route.
Casparian strip is the barrier that blocks the passage of minerals into the vascular cylinder it forces water and minerals that are passively moving through the apoplast to cross the plasma membrane of the endodermal cell before they can enter the vascular cylinder.
What is a stomata? How do the stomata regulate the water content in a plant?
95% of water escapes through stomata spores on the outer leaf skin layer. The waxy cuticle limits water loss through the remaining surface of the leaf. Each stomata is flanked by a pair of guard cells.
why does the stomata is open during the day, and why the stomata is (mostly) closed during the night.
STOMATA OPEN WHEN GUARD CELLS ACTIVELY ACCUMULATE K+ which is stimulated by light. from neighboring epidermal cells. Stomata closing results from a loss of K+ from guard cells to neighboring cells which leads to an osmotic loss of water.
Stomata is closed during the night to prevent the plant from losing water when photosynthesis cannot occur. They open at dawn because there is light , CO2 depletion, and an internal “clock” in guard cells.
What is the shape of the guard cells when they are flaccid? How does this affect the stomata?
Stomata is closed
What is the shape of the guard cells when they are turgid? How does this affect the stomata?
Stomata opens- the radial orientation of cellulose microfibrils in the cell walls causes the guard cells to increase more in length than width when turgor increases