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Life of Earth 2 > Plant nutrition > Flashcards

Plant nutrition Flashcards

1
Q

What is plant nutrition?

A

The study of the chemical elements necessary for plant growth & the adaptations for obtaining these elements

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2
Q

80-90% of a plant’s fresh mass is what?

A

Water

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3
Q

4% of a plant’s dry mass is what?

What is the other 96%?

A

Inorganic substances from soil

From CO2 assimilated during photosynthesis

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4
Q

What are essential elements?

A

Required for plants to survive (complete its life cycle) & reproduce

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5
Q

What % do micronutrients make up in some species?

A

0.02% of dry weight

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6
Q

What are most fertilisers?

A

NPK

= major macronutrients essential for healthy plant growth

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7
Q

Give examples of macronutrients

A 
Carbon
Oxygen 
Hydrogen 
Nitrogen 
Potassium 
Calcium 
Magnesium 
Phosphorous 
Sulfar
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8
Q

Give an example of a micronutrient and what it’s used for

A

Manganese

- crucial for amino acid formation & photosynthesis

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9
Q

Which is the most abundant macronutrient that isn’t C, H or O2?

A

Nitrogen

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10
Q

What is N a component of?

A 
Amino acids
Nucleic acids
Cofactors
Hormones
Alkaloids
Chlorophyll
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11
Q

What is hydroponic culture used for?

A

Determining which chemical elements are essential

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12
Q

What do symptoms of mineral deficiency depend on?

A

Nutrient’s function & mobility within the plant

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13
Q

What does deficiency of a mobile nutrient affect?

Give an example

A

Older organs

Magnesium

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14
Q

What does deficiency of an immobile nutrient affect?

Give an example

A

Younger organs

Iron

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15
Q

Why are older organs affected more in mobile nutrient deficiency?

A

Mobile nutrients can be transported to actively growing young tissues from older tissues
- so older organs display the deficiency

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16
Q

What are the most common deficiencies?

A

N
P
K

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17
Q

What is a key factor that affect nutrient availability?

A

pH

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18
Q

In which pH are there:
> major nutrient deficiencies?
> trace element deficiencies?

A

> Acidic

> Alkaline

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19
Q

How do some species survive in acidic & alkaline soils?

A

> ability to interact w/ other orgs in soil

> can change chemistry of soil around them to facilitate getting hold of macronutrients

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20
Q

Define chlorosis

A

Yellowing due to loss of chlorophyll

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21
Q

Define necrosis

A

Death of plant tissue

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22
Q

What are the symptoms of N deficiency?

A

> little growth

> yellowing of mature lower leaves

23
Q

What type of nutrient is N?

A

Mobile macronutrient

24
Q

What are the 2 forms N is acquired in?

A

> nitrate - favoured as benign & chemically unreactive

> ammonia - toxic as breaks down e- transport

25
Q

Soil is stratified into layers called…?

A

Soil horizons

26
Q

Which horizon plants obtain most of their water & minerals from?

A

A horizon

- topsoil

27
Q

What does topsoil consist of?

A

> mineral particles
living orgs
humus (decaying organic material)

28
Q

What are the basic physical properties of soil?

A

Texture

Composition (organic & inorganic)

29
Q

What is the B horizon made up of?

A

Less organic material than A

Less weathered than A

30
Q

What is the C horizon made of?

A

Partially broken down rock

31
Q

Why can clay particles hold onto water?

A

They’re -vely charged

32
Q

How is soil formed?

A

By gradual disintegration of rocks

+ decaying organic matter integrates into soil aggregates

33
Q

What are cations?

Give examples.

What do they do to soil particles & why?

A

+ve charged ions

K+, Ca2+,Mg2+

Adhere to them
Particles are -vely charged

34
Q

What happens in cation exchange?

A

Cations are displaced from soil particles by H+ ions produced directly or indirectly by plant roots

  • -> displace cations enter soil solution
  • -> can be taken up by plant roots
35
Q

How can H+ ions be released indirectly by plant roots?

A

CO2 from respiration released from plant roots

  • -> produces carbonic acid
  • -> releases H+ ions
36
Q

How can plant nutrition sometimes depend on mutualistic relationships w/ soil microbes?

A

> secretions from roots support microbes in nearby enviro

> microbes in rhizosphere help plant obtain nutrients

37
Q

What are endophytic bacteria?

A

Those that live between cells in plant roots

38
Q

What is the rhizosphere?

A

Layer of soil surrounding the growing root that is affected by the root
- no sharp boundary

39
Q

What is rhizodeposition?

A

The secretion of organic compounds e.g. sugars, amino acids & organic acids by plant roots into the rhizosphere

40
Q

What do rhizodeposits consist of?

A

> sloughed off cells (by friction w/ soil)

> organic matter exuded (from living cells)

41
Q

Why is rhizodeposition of ecological importance?

A

> loss of C for the plant
input from organic C pool of the soil
field the soil microbiota

42
Q

What are rhizobacteria?

A

Bacteria that live in the rhizosphere

43
Q

What are the roles of rhizobacteria?

A

> produce hormone-like substances = stimulate plant growth
produce antibiotics = protect roots from disease
absorb toxic metals/ make nutrients more available to roots

44
Q

What are the roles of soil bacteria in plant N nutrition?

A

N-fixing bacteria e.g. Rhizobia
(N gas –> ammonia)

Ammonifying bacteria
(humus –> ammonia)

Nitrifying bacteria
(ammonium –> nitrate)

Denitrifying bacteria
(nitrate –> N gas)

45
Q

Why isn’t N directly available to plants?

A

Requires breaking of v stable covalent triple bond

plants can’t do

46
Q

What are mycorrhizae?

A

Mutualistic associations of fungi & roots

  • increase absorption capacity of plant
  • fungi gain carbohydrates
47
Q

What are the 2 types of mycorrhizae?

A

Ectomycorrhizae
- grows on surface of roots & between cells

Endomycorrhizae
(arbuscular mycorrhizae)
- gets into cytoplasm of cell

48
Q

What are the nutritional adaptations using other orgs in a non-mutualistic way?

A

Epiphytes
Parasitic plants
Carnivorous plants

49
Q

What are epiphytes?

A

Plants that grow on surface of plants and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it.

50
Q

What are the different examples of types of parasitic plants?

A

Mistletoe = photosynthetic

Dodder = non photosynthetic

Indian pipe = non photosynthetic parasite of mycorrhizae

51
Q

Describe carnivorous plants

A

> Photosynthetic
Obtain N by killing & digesting insects
Adaptation to low nutrient enviro e.g. bogs
Traps = modified leaves

52
Q

What are the 2 types of traps & give examples

A

Active
e.g. Venus fly trap

Passive
e.g. Pitcher plants

53
Q

What are the costs of botanical carnivory?

A

> underdeveloped root system
traps not v good at photosynthesis

= trade-off between light capture & prey capture

Life of Earth 2 (20 decks)

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