Lecture #5 Plant Nutrition

Question 1

How do plants take up nutrients through their roots

Answer 1

Through mycorrhizae and root hairs they absorb water and minerals from the soil

Question 2

How do plants take up nutrients through their leaves

Answer 2

Carbon dioxide diffuses into leaves from the surrounding air through the stomata

Question 3

How many essential nutrients do plants need

Answer 3

17 they need nine macro nutrients and at least eight micro nutrients

Question 4

What are macronutrients

Answer 4

Elements required by plants in relatively large quantities (carbon oxygen hydrogen nitrogen sulfur and phosphorus also potassium calcium and magnesium)

Question 5

What are micro nutrients

Answer 5

elements that plants need in very small amounts for example iron chlorine copper zinc magnesium molybdenum boron and nickel)

Question 6

What is chlorosis

Answer 6

It is the deficiency of magnesium a key component of chlorophyll which causes yellowing of the leaves. It can also be caused by iron deficiency

Question 7

Where are mineral deficiency symptoms show me first

Answer 7

In the older tissues because the younger growing tissues have more drawing power

Question 8

What is topsoil

Answer 8

A mixture of rock, living organisms and humus which is the residue of partially decayed organic material

Question 9

What are horizons

Answer 9

Distinct layers of soil

Question 10

Humic acid chemicals contain…

Answer 10

positive, negative and neutral sites: cation, an ionic attraction

Question 11

What is humus

Answer 11

decomposing organic material formed by bacteria and fungi on dead organisms, feces, falling leaves and other organic refuse. It prevents clay from parking together and build a crumbly soil

Question 12

Minerals especially ones with a positive charge such as potassium calcium, and magnesium, adhere by electrical attraction to the negatively charged surfaces of clay particles

Answer 12

Minerals that are negatively charged such as nitrate, phosphate, and sulfate, are usually not bound tightly to soil particles and thus tend to leach away quickly

Question 13

what is cation exchange

Answer 13

When positively charged mineral ions are made available to the plant when hydrogen ions in the soil displays the mineral ions from the clay particles

Question 14

What are the most fertile soil’s

Answer 14

Loam soil’s(equal amounts of sand , silt and clay) Because they have fine particles to provide a large surface area for retaining been rules and water which here to the particles. They also have enough coarse particles to provide air spaces that supply oxygen to the root for cell respiration

Question 15

How can inadequate drainage impact survival of many plants

Answer 15

Plants can suffocate air spaces are replaced by water

Roots can also be attacked by molds favored by the soaked soil

Question 16

Can the activities of organisms affect physical and chemical properties of the soil

Answer 16

Yes

Question 17

What forms of nitrogen can plants use

Answer 17

Ammonium NH4+ or nitrate NO3- So the main source of nitrogen is the decomposition of humus by microbes including the bacteria and fungi

Question 18

What is nitrogen fixation

Answer 18

A process where nitrogen fixing bacteria restock nitrogenous materials in the soil by converting N2 to NH3 (ammonia)

Question 19

What is nitrogenase

Answer 19

an enzyme complex that catalyzes nitrogen fixation

Question 20

How does NH3 (ammonia) turn into NH4+ (ammonium)?

Answer 20

It picks up another hydrogen ion in the soil solution

Question 21

How is nitrate formed? (NO3-)

Answer 21

when ammonium (NH4+) is oxidized by nitrifying bacteria in the soil

Question 22

what does symbiotic Nitrogen fixation result from?

Answer 22

Intricate interactions between routes and bacteria (mainly legume family)

Question 23

What’s a nodule?

Answer 23

legumes root swellings composed of plant cells that contain nitrogen fixing bacteria of the genus rhizobium

Question 24

What are bacteriods?

Answer 24

Form a rhizobium bacteria inside the nodule

Question 25

Development of root nodules

Answer 25

1) Chemical signals from the route attract rhizobium, begin infection thread
2) bacteria penetrate the root cortex within the infection thread
3) cortex and pericycle fuse fuse after growth and form nodule
4) nodule grows, vascular tissue connects it to xylem and phloem

Question 26

How is the process of nodule formation started

Answer 26

1. Flavonoid signal travels from root to Rhizobium
2. activates gene regulator (Nod D.)
3. Nod. D binds to nod box, activated transcription of nod genes
4. Nod genes produce metabolic enzymes
5. Produces Nod factor, which travels to root and triggers infection thread

Question 27

What are nod factors similar to

Answer 27

chitin

Question 28

How can farmers ensure the formation of nodules

Answer 28

soak culture in rhizobium

Question 29

How is the symbiotic relationship between a legume and nitrogen fixing bacteria mutualistic

Answer 29

Bacteria supply the legume with fixed nitrogen and the legume provides the bacteria with carbohydrates and other organic compounds

Question 30

What are mycorrhizae

Answer 30

Modified roots consisting of symbiotic associations of fungi and roots (fungus roots)

Question 31

how is mycorrhizae mutualistic

Answer 31

The fungus benefits from a hospital environment and steady supply of sugar

The plant benefits from phosphate and other minerals supplied to it and also growth factors that are secreted by the fungi to stimulate growth and also antibiotics that may help protect the plant from pathogenic bacteria and fungi in the soil

Question 32

why do almost all plant species produce mycorrhizae

Answer 32

Because he made it possible for plants to colonize land in the first place and are Efficient at absorbing minerals

Question 33

What are the two forms of mycorrhizae

Answer 33

ectomycorhizae: mycelium forms dense sheath over the surface of the root and some hyphae grow into the cortex in extracellular spaces between root cells (common in woody plants)

and

endomycorhizae: The fungus makes extensive contact with the plant through branching of hyphae (aburcles) that form invaginations in the host cells increasing surface area for exchange of nutrients