BIOLOGY 3 Marks Question

The plants which show symptoms due to the deficiency of more than one nutrient are grown in different sets in water culture. Set 1 is given one of the several nutrients showing deficiency symptoms, set 2 is given another nutrient and set 3 is given yet another nutrient. In this way, the different sets are grown in hydroponics by supplementing one of the different nutrients showing deficiency. The real deficient mineral element, if supplemented in the medium, causes plants to grow under normal conditions reverting the deficiency symptom.

Most of the mineral elements present in the soil enter plants through roots but all of these may not be essential for their survival. Some are absorbed and accumulated by plant only because they are present in excess amount. For example plants growing near nuclear test sites take up strontium, even though it is not required by them. Thus, an essential element is that which is necessary for supporting normal growth and reproduction, its requirement must be specific i.e. its deficiency cannot be met by supplying other element and it must be directly involved in the metabolism of plant.

Impure water contains a large number of impurities in the form of soluble minerals dissolved in it. Salts also contain impurities. If such impure water and mineral salts are used as solution culture for growing plants in hydroponics, then these impurities interfere with the experiments used for detection of essentiality of an element. Therefore, purified water and purified nutrient salts are used in studies involving mineral nutrition using hydroponics.

1. Calcium is a macroelement.
2. Most of the calcium is required in cell vacuoles and parts bounded in cell walls. It is also required in the meristematic tissues of roots, stems and leaves.
3. Calcium deficiency in plants causes degeneration of fruits, the blossom in tomatoes and termination of growth of meristematic regions.

Functions: For normal growth of cell membranes. Control cell permeability.

4. Rashi is a patient listner, attentive, intelligent, and careful about daily life.

Carnivorous plants fulfill their nutritional requirements by feeding on small animals, like insects or protozoan’s. E.g., Nepenthes, Venus fly trap, Utricularia, etc. Carnivorous, plants grow in soil deficient in nitrogen. Pitcher plant in pitcher plant leaves are modified into pitcher which stores the juice to lure an insect. When an insect comes to suck this juice, chemicals present in nectar dissolves the skin of the prey and the plant obtains nutrients (mainly nitrogen) from its skin.

1. Nostoc, Anabaena.
2. Azotobacter, Beijerinckia.
3. Frankia, Rhizobium.

Differences between passive and active salt absorption are:

S. No.	Passive Salt Absorption	Active Salt Absorption
1.	Does not need energy.	Requires expenditure of energy.
2.	Occurs along chemical and electrochemical gradient.	Occurs against chemical and electrochemical gradient.
3.	Passive salt absorption is a physical process in which accumulation of salts is less.	Active salt absorption is a biochemical process in which accumulation of salts is more.

1. Only some trees show those symptoms because, they were deficient in the element nitrogen.
2. Nitrogen plays a significant role in plants by acting as an important component of protein, chlorophyll, cytochromes, auxin, DNA, RNA, NAD, etc. It promotes the vegetative growth of the plants.
3. Necrosis is the phenomenon that often leads to the death of tissues, cell or organ (mainly leaf) while it is still a part of living plant.
4. Values concerned with the excercise is that Sangeeta is caring about the plants in her garden and has scientific knowledge about nutrients. Also a good observer.

1. The symptom of manganese toxicity is the appearance of brown spots surrounded by chloritic veins.
2. Manganese toxicity leads to deficiency symptoms of iron, magnesium and calcium, for the following reasons:

• Manganese competes with the uptake of iron and magnesium
• It also competes with magnesium for binding with enzymes.
• It inhibits translocation of calcium to shoot apex.

2. Cooperation is always good for mutual benefit.

Explanation:
Cooperation has many benefits for humans. All of us live in complex society and everybody is dependent on others for most of the needs. Let us take example of the most basic need; the food. We get raw materials; like rice, flour, vegetables, etc. from the shopkeeper. The shopkeepers, in turn, get those materials from different suppliers. We may be living in one corner of the country and using something produced in another corner of the country. This becomes possible because of cooperation among different human beings. Even for our study, we depend on many people; like teachers, school staffs, stationery shops, stationery manufacturers, etc.

1. This figure is showing the technique of hydroponics. This was first demonstrated by Julius von Sachs in 1860.
2. This technique can commercially applied for many plants. Three of them are as follows: Tomato, seedless cucumber and lettuce.
3. The aerating tube supplies oxygen to the roots. Feeding funnel is used to add water and nutrients as per requirement.

Hydroponics appears to be a successful technique for commercial production of plants. Many plants have been grown using this technique. But crops are still grown on land because of certain limitations of hydroponics.

1. Hydroponics is still at experimental stage and more developments need to happen before it can be used on mass scale.
2. The initial cost of set up is very high and thus growing plants through technique cannot be commercially viable.
3. There is frequent problem of maintaining a high level of sterilization while growing plants through this technique.
4. Plants grown through this method need frequent input of nutrients and air which is highly cumbersome at present.
5. Plants can be highly susceptible to environmental conditions because they are being grown in laboratory conditions.

1. Essential elements are those which are required by the plant in appropriate amount in order to get proper growth and development. Thus, their absence may lead to deficiency of one or the another type.
2. Basic criteria for essentiality are:

• The element must be able to provide appropriate normal growth and reproduction.
• The requirement of the elements must be specific and should not be replaceable by one or the another element.

3. Some essential elements are carbon, hydrogen, oxygen, nitrogen, sulphur, potassium, phosphorus, zinc, magnesium, etc.
4. Values associated with Rajeev's character are consciousness about the topic, careful, curious to know new things.

1. Inorganic nutrients are called mineral nutrients because these are derived from the weathering of minerals of rocks.
2. Functions of soil are:

• Hold water and supplies air to the roots.
• Acts as matrix that helps in stabilisation of plant.

3. The ions are absorbed either by active or by passive absorption.
4. Values indicated from the behaviour of Ravi's tutor are critical thinking about natural phenomenon, scientific knowledge.

The nitrogen cycle involves the following steps:

1. Nitrogen fixation:

• It is the process of conversion of atmospheric free nitrogen into ammonia and other nitrogenous compounds.
• It is carried out by soil microbes like Azotobacter, Azospirillum and Rhizobium.
• Lightning and ultraviolet rays provide energy for conversion of nitrogen into oxides of nitrogen.

2. Ammonification: It is the process of decomposition of organic nitrogenous compounds into ammonia.
3. Nitrification: It is the process of converting ammonia first into nitrite (by Nitrosomonas, Nitrococcus) and then into nitrate (by Nitrobacter).
4. Denitrification:

• It is the process of conversion or reduction of nitrates in the soil to free nitrogen.
• It is carried out by bacteria like Thiobacillus and Pseudomonas.

1. We should protect the ecosystem so that its balance is maintained.

Explanation:
We are the most advanced species on this earth and have the capability to think. So, it becomes our responsibility to maintain the ecosystem.
The balance of the ecosystem is important for all the living beings and more so for human beings. We should remember that we are directly or indirectly dependent on various components of the ecosystem for our survival. Even if a seemingly inconspicuous material's balance is disturbed in the ecosystem, it can prove disastrous for us. Let us take example of carbon dioxide. Carbon dioxide is a very useful gas. Carbon dioxide traps solar radiation and prevents it from escaping the atmosphere of the earth and thus maintains an ambient temperature on the earth. Carbon dioxide is an important raw material for photosynthesis and is thus important for the survival of life on this earth. But when the same carbon dioxide becomes more than what is required, it can prove dangerous for us. A higher level of carbon dioxide would lead to global warming which would threaten the life on the earth.

1. Since the inorganic elements involved in plant nutrition are derived from the rock minerals during weathering of rocks, plant nutrition is referred to as mineral nutrition.
2. Role of soil in plant growth:

• Soil supplies the mineral nutrients to plants.
• It holds water that is absorbed by plants.
• It supplies air to the roots.
• It harbours microbes involved in nitrogen fixation, nitrification and other processes that enrich soil fertility.
• It acts as a matrix that stabilises the plants.

	Critical Concentration	Deficient
	A concentration of a nutrient measured in tissue, just below the level that gives maximum growth is defined as, critical concentration. e.g., N, P and K are known as critical elements.	The concentration that is below the critical concentration and the deficiency of nutrient element can lead to a gradual fall in the plant growth is called deficient.
Zn	0.5-1%	Less then 0.5%
Fe	3.5-5%	Less than 3.5%

1. It plays an important role in protein synthesis, photosynthesis, respiration, growth and almost all the metabolic processes.
2. Utricularia and Nepenthes.
3. These plants are autotrophic in nature. The strange thing about them is that, inspite of being autotrophs they behave like heterotrophic organisms by trapping insects.
4. Values that imbibe from Kirti's character are org curiousness and excitation to know about our surroundings and consciousness towards nature.