XI Chap 12 Mineral Nutrition Flashcards
(130 cards)
1
Q
In _______, a prominent German botanist named ________ demonstrated for the first time that plants could be grown to maturity in a defined nutrient solution, complete absence of soil.
A
1860, Julius von Sachs
2
Q
The technique of growing plants in nutrient solution is known as _____________
A
hydroponics
3
Q
When studying mineral nutrients for plants, why is purified water and mineral nutrient salts essential?
A
Rule out other influencing factors
4
Q
Hydroponics is not yet successfully employed towards COMMERCIAL production of vegetables. T or F?
A
False, has been e.g. tomato, seedless cucumber and lettuce
5
Q
Nutrient solutions must be adequately _______ to obtain the optimum growth
A
aerated
6
Q
All minerals present in soil can enter plants through roots. T or F?
A
False, most can
7
Q
More than ___ elements out of ____ discovered so far are found in plants
A
60, 105
8
Q
Some plant species accumulate selenium, gold and even radioactive strontium. T or F?
A
True
9
Q
There are techniques that are able to detect the minerals even at very low concentrations (10 ^ -11 g / mL). T or F?
A
False, 10 ^ -8g/mL
10
Q
Plants grown in a tube or trough are placed at a __________
A
slide incline
11
Q
In hydroponic plant production, a ______ circulates nutrient solution from a reservoir to ________ of the tube
A
pump, elevated end
12
Q
In hydroponic plant production, nutrient solution flows down the tube and returns to reservoir due to ________
A
gravity
13
Q
What are the criteria for essentiality of an element?
A
- Must be absolutely necessary for growth and reproduction
- In absence, life cycle cannot be completed / seeds cannot be set
- Not replaceable by any other element
- Must be DIRECTLY involved in metabolism
14
Q
Essential elements are divided into 2 categories based on their quantitative requirements. They are?
A
Macronutrients (large amounts) and micronutrients (trace amounts)
15
Q
Macronutrients include? (9)
A
Carbon, hydrogen, oxygen Nitrogen Phosphorus Sulphur Potassium Calcium Magnesium
16
Q
Macronutrients are in excess of ______ whereas micronutrients are less than than amount
A
10 mmole / Kg of DRY matter
17
Q
Carbon, hydrogen and oxygen in plants are mainly obtained from
A
carbon dioxide and water
18
Q
Macronutrients other than C, H and O are obtained from ________
A
soil
19
Q
Micronutrients include? (8)
A
Fe, iron Mn, manganese Cu, copper Mo, molybdenum Zn, zinc B, boron Cl, chlorine Ni, nickel
20
Q
How many essential elements are there?
A
21
17 + sodium, silicon, cobalt and selenium (higher plants)
21
Q
What additional elements are required by higher plants as essential nutrients?
A
Silicon, Selenium, Sodium, Cobalt
22
Q
Essential elements can be grouped in __ categories based on their functions. What are they?
A
4;
- Components of Biomolecules (structural elements)
- Components of energy-related chemical compounds e.g. ATP
- Activators/inhibitors of enzymes
- Alter the osmotic potential of cell (solutes)
23
Q
What are the essential nutrients that function as structural elements for plant cells?
A
C, H, O and N
24
Q
What are the essential nutrients that function as component of energy-related chemical compounds?
A
Mg - chlorophyll
P - ATP
25
What are the essential nutrients that function as enzymatic activators/inhibitors?
Mg2+ - activator for RuBisCo and phosphoenol pyruvate carboxylase
Zn2+ - activator for alcohol dehydrogenase
Mo - nitrogenase (nitrogen metabolism)
26
What are the essential nutrients that alter osmotic potential of plant cells?
Potassium - opening/closing of stomata
| Other solutes
27
What are the forms and functions of Nitrogen?
mainly NO3- (nitrate) or NO2- or NH4+
functions: constituent of proteins, nucleic acids and amino acids, vitamins and hormones, chlorophyll
28
_________ is the essential nutrient required in greatest amount
Nitrogen
29
Nitrogen is required particularly in __________ tissues and ______________ cells
meristematic tissues, metabolically active cells
30
What are the forms and functions of Phosphorus?
Phosphate ions: H2PO4- or HPO4 2-
constituent of cell membranes, certain proteins, all nucleic acids and nucleotides, all phosphorylation reactions
31
What are the forms and functions of Potassium?
Potassium ion (K+)
Maintain an anion-cation balance in cells, protein synthesis, opening and closing of stomata, activation of enzymes and maintenance of cell turgidity
32
Potassium is required in more abundant quantities in _______ tissues, ___, ____ and ______.
meristematic tissues, buds, leaves, and root tips
33
What are the forms and functions of Calcium?
Calcium ions (Ca2+)
During cell division - synthesis of cell wall, formation of mitotic spindle; normal functioning of cell membranes; enzyme activation; regulation of metabolic activities
34
_________ nutrient accumulates in older leaves
Calcium
35
During cell division, calcium is particularly used as __________ in the __________
calcium pectate, middle lamella
36
What are the forms and functions of Magnesium?
Divalent Mg2+
activates respiration enzymes, photosynthesis, DNA/RNA synthesis, ring structure of chlorophyll, maintain ribosome structure
37
What are the forms and functions of Sulphur?
Sulphate (SO4 2-)
constituent of 2 amino acids - cysteine and methionine;
constituent of several coenzymes (Coenzyme A);
vitamins (thiamine, biotin), and;
ferredoxin (protein)
38
What are the forms and functions of Iron?
Ferric ions (Fe3+)
constituent of proteins involved in electron transfer (e.g. ferredoxin, cytochromes); activates catalase enzyme; formation of chlorophyll
39
______ is the macronutrient required in largest amounts, ______ is the micronutrient required in largest amounts
N, Fe
40
Iron is reversible oxidised from Fe3+ to Fe2+ during electron transfer. T or F?
False, Fe2+ to Fe3+
41
What are the forms and functions of Manganese?
Manganous ions (Mn2+)
Splitting of water during photosynthesis(!!); activates enzymes involved in photosynthesis, respiration and nitrogen metabolism
42
What are the forms and functions of Zinc?
Zn2+ ions
activates various enzymes (esp. carboxylases), synthesis of auxin
43
What are the forms and functions of Copper?
Cupric ions (Cu2+)
overall metabolism in plants; enzymes involved in redox reactions
44
Copper is irreversibly oxidised from Cu+ to Cu2+. T or F?
False, reversibly
45
What are the forms and functions of Boron?
BO3 3- or B4O7 2-
uptake and utilisation of Ca2+, membrane functioning, pollen germination, cell elongation, cell differentiation and carbohydrate translocation
46
What are the forms and functions of Molybdenum?
Molybdate ions (MoO2 2+)
component of several enzymes (nitrogenase and nitrate reductase - nitrogen metabolism)
47
What are the forms and functions of Chlorine?
Chlorine anion (Cl-)
determining the solute concentration, anion-cation balance in cells, water-splitting reaction in photosynthesis
48
Water-splitting reaction in photosynthesis leads to _______ evolution
oxygen
49
Apart from Chlorine and Potassium, what is the third ion required to determine solute concentration and anion-cation balance in cells?
Na+
50
Nutrients required in meristematic tissues? (3)
Ca, N, K
51
Nutrients required in proteins/protein synthesis? (4)
P, Fe (electron transfer), N, K
52
Nutrients required in photosynthesis? (3)
Mg, Mn, Cl
53
What is critical concentration?
Concentration of essential element below which plant growth is retarded
54
Element is said to be ________ when below critical concentration
deficient
55
Morphological changes indicative of certain element deficiencies are called ________
deficiency symptoms
56
Deficiency symptoms are reversible but if deprivation of element continues, then may lead to _______
death
57
For elements actively mobilized and exported to young tissues, deficiency symptoms appear first in _____
older tissues
58
Deficiency symptoms of N, K and Mg are first visible in_______ leaves
senescent
59
Deficiency symptoms tend to appear first in young tissues whenever elements are _______
relatively immobile
60
Sulphur and calcium are both relatively immobile structural elements. T or F?
True
61
Kind of deficiency symptoms shown in plants are:
```
chlorosis
necrosis
stunted growth
premature fall of leaves and buds
inhibition of cell division
```
62
Chlorosis is?
loss of chlorophyll => yellowing leaves
caused by deficiency of:
S, Mo, K, N, Mg
Fe, Mn, Zn
63
Necrosis is?
death of tissue, particularly leaf tissue
| due to deficiency of Ca, Cu, K, Mg
64
Lack or low level of __________ causes inhibition of cell division
S, Mo, K, N
65
_______ delay flowering if their concentration in plants is low
S, Mo, N
66
Deficiency of any element can cause multiple symptoms. T or F?
True
67
Deficiency of each element leads to unique deficiency symptoms. Same symptom cannot be caused by two different element deficiencies. T or F?
False, same symptoms may be caused by multiple elements
68
Moderate increase of micronutrients causes _______
toxicity
69
Why is there a narrow optimum range of concentration for elements?
decrease => deficiency
| increase => toxicity
70
_________ symptoms are difficult to identify.
| toxicity or deficiency
Toxicity
71
________ is the prominent symptom of manganese toxicity.
Brown spots surrounded by chlorotic veins
72
Mn competes with ___ and ____ for uptake and with ____ for binding with enzymes.
Fe and Mg,
| Mg
73
________ inhibits calcium translocation in shoot apex
Mn
74
Excess of Mn may induce deficiencies of ...?
Mg, Fe, Ca
75
Much of the studies on mechanism of absorption have been carried out in ______ cells, tissues or organs.
isolated
76
Two phases of process of absorption?
1. Rapid uptake - free / outer space of cells (apoplast) - passive
2. Slow uptake - inner space - symplast - active
77
Passive movement of ions into apoplast occurs through _____, transmembrane proteins that function as selective pores
ion-channels
78
Movement of ions is usually called _____
flux
79
Influx / efflux?
Influx - into the cell
| efflux - out of cell
80
Nutrients become available to roots in soil due to ________ and _______ of rocks
weathering, breakdown
81
Functions of soil:
- supply minerals
- harbours nitrogen-fixing bacteria
- harbours other microbes
- holds water
- supplies air
- matrix that stabilises plant
82
Fertilisers only contain macronutrients. T or F?
False, both macro and micro come in ferilisers
83
Plants compete with ______ for the limited nitrogen in soil.
Microbes
84
Nitrogen exists as ___ nitrogen atoms joined by a very strong ________ bond
2, triple covalent
85
What is nitrogen-fixation?
Conversation of N2 to ammonia
86
In nature, _____ and ______ provide enough energy to convert nitrogen to nitrogen oxides
lightning and UV radiation
87
What are the 3 nitrogen oxides?
NO, NO2, N2O
88
Man-made sources of atmospheric nitrogen oxides are:
forest fires
automobile exhausts
industrial combustions
power-generating stations
89
What is ammonification?
Decomposition of organic N of dead plants/animals into ammonia
90
Some of the ammonia from ammonification _____ but most of it is converted into ______ by soil bacteria
volatilises and re-enters atmosphere;
| nitrate
91
2NH3 + 3O2 ---> 2NO2- + 2H+ 2H2O
2NO2 + O2 ---> 2 NO3-
What do these equations represent?
nitrification
ammonia --> nitrite in first step
further oxidised to nitrate
92
Ammonia is first oxidised to nitrite by _________ (bacteria) and further oxidised to nitrate by ______ (bacteria)
Nitrosomonas and/or Nitrococcus
| Nitrobacter
93
Nitrifying bacteria are _________trophs
chemoautotrophs
94
Nitrate absorbed by plants is _____ in leaves to form ammonia that finally forms the ______ group of amino acids.
reduced, amine group
95
Nitrate in the soil is also reduced to nitrogen by process of ______ carried out by bacteria _______
denitrification,
| Pseudomonas and Thiobacillus
96
Very few living organisms can utilise nitrogen in the form N2 available abundantly in air. T or F?
True
97
Only _______ are capable of fixing nitrogen
certain prokaryotic species
98
What is biological nitrogen fixation?
Reduction of nitrogen to ammonia by living organisms
99
Enzyme ________ capable of nitrogen reduction is present exclusively in _______
nitrogenase, prokaryotes
100
Nitrogen fixing microbes could be free-living or symbiotic. T or F?
T
101
Match the following:
```
Beijerinckia
Rhizobium
Anabaena
Azotobacter
Rhodospirillum
Nostoc
Frankia
```
free-living OR anaerobic free-living OR cyanobacteria free-living OR symbiotic
```
Beijerinckia - free-living
Rhizobium - symbiotic
Anabaena - cyanobacteria free-living
Azotobacter - free-living
Rhodospirillum - anaerobic free-living
Nostoc - cyanobacteria free-living
Frankia - symbiotic
```
102
Most prominent symbiotic biological nitrogen-fixing association is? And most common form of association is?
Legume-bacteria (Rhizobium)
| Nodules
103
Rhizobium has symbiotic relationship with which plants (7)?
```
alfalfa,
sweet clover,
sweet pea,
lentils,
garden pea,
broad bean,
clover beans
```
104
Frankia produces nitrogen-fixing nodules on roots of __________ e.g. ____
non-leguminous plants e.g. Alnus
105
Rhizobium and Frankia are free-living in soil as well as can be symbionts. T or F?
True
106
What makes symbiont nodules pink?
Presence of leg-haemoglobin
107
How does nodule formation occur?
1. Rhizobia multiply and colonise root surroundings, get attached to epidermal and root hair cells
2. Root hairs curl, bacteria invade root hair
3. Infection thread carrying bacteria into cortex, where they initiate nodule formation
4. Bacteria release from thread into cells, modified into rod-shaped bacteroids => inner cortical and pericycle cells to divide => differentiation of specialized nitrogen fixing cells
5. mature nodule formed with direct vascular connection with host
108
Nodule contains all necessary biochemical components such as enzymes _____ and _____
nitrogenase, leghaemoglobin
109
Enzyme nitrogenase is a ____ protein that catalyses the conversation of _______ to _____
Mo-Fe,
| nitrogen to ammonia
110
_____ is the first stable product of nitrogen fixing
Ammonia
111
The enzyme nitrogenase is highly sensitive to _________ and requires _______ conditions
oxygen, anaerobic
112
Leg-haemoglobin is a ______ scavenger that protects nitrogenase
oxygen
113
Nitrogenase is operational in nodule forming bacteria in free-living conditions and as symbionts. T or F?
False, only in symbionts
114
Nitrogen fixation is reduction reaction that requires very high amount of ATP. T or F?
True
115
___ ATP are required for each NH3 produced
8
116
_____ ATP are required for each N2 atom that is reduced
16
117
Energy required for nitrogen fixation is obtained from _________ process of host.
Respiration
118
At physiological pH, ammonia is ________ to form _________
protonated, NH4+ ions
119
Most plants can assimilate both nitrates as well as ammonium ions. T or F?
True
120
Ammonium ions are quite toxic to plants, cannot accumulate in them and are hence used to synthesise _________
amino acids
121
Two ways to use ammonium ions to synthesise amino acids?
1. Reductive amination - ammonia reacts with alpha-ketoglutaric acid to form glutamic acid
2. Transamination - transfer of amino group from one amino acid to keto group of a keto acid.
122
_______ is the main amino acid from which transfer of NH2, the amino group takes place.
Glutamic acid
123
Enzyme ______ catalyzes all reactions in transamination
transaminase
124
The two most important amides in plants are ____ and ______. What function do they play?
asparagine, glutamine;
| structural parts of proteins
125
Asparagine is the amide formed from _______; glutamine from _______ by addition of ________
aspartic acid;
glutamic acid;
another amino group
126
The hydroxyl part of glutamic or aspartic acid is replaced by ___________ in formation of amides.
Another NH2- radicle
127
Why are amides transported to other parts of plants via xylem?
Since they contain more nitrogen than amino acids
128
Along with transpiration stream, nodules of some plants like soyabean export the fixed nitrogen as _______ which have a particularly high nitrogen to ____ ratio.
ureides, carbon
129
Not all minerals absorbed are required by plants. T or F?
True
130
Nitrogen fixation requires a strong oxidising agent and energy in the form of ATP. T or F?
False, strong reducing agent
