What are the steps involved in formation of a root nodule?
Question: What are the steps involved in formation of a root nodule? Solution: Multiple interactions are involved inthe formation of root nodules. TheRhizobiumbacteria divide and form colonies. These get attached to the root hairs and epidermal cells. The root hairs get curled and are invaded by the bacteria. This invasion is followed by the formation of an infection thread that carries the bacteria into the cortex of the root. The bacteria get modified into rod-shaped bacteroides. As a result, ...
Read More →What does atomic radius and ionic radius really mean to you?
Question: What does atomic radius and ionic radius really mean to you? Solution: Atomic radius is the radius of an atom. It measures the size of an atom. If the element is a metal, then the atomic radius refers to the metallic radius, and if the element is a non-metal, then it refers to the covalent radius. Metallic radius is calculated as half the internuclear distance separating the metal cores in the metallic crystal. For example, the internuclear distance between two adjacent copper atoms in...
Read More →What are the conditions necessary for fixation of atmospheric nitrogen by Rhizobium.
Question: What are the conditions necessary for fixation of atmospheric nitrogen byRhizobium.What is their role in N2-fixation? Solution: Rhizobiumis a symbiotic bacteria present in the root nodules of leguminous plants. The basic requirements forRhizobiumto carry out nitrogen fixation are as follows: (a)Presence of the enzyme nitrogenase (b)Presence of leg-haemoglobin (c)Non-haem iron protein, ferrodoxin as the electron-carrier (d)Constant supply of ATP (e)Mg2+ions as co-factors Rhizobiumcontai...
Read More →How are the minerals absorbed by the plants?
Question: How are the minerals absorbed by the plants? Solution: The absorption ofsoil nutrients by the roots of plants occurs in two main phases apoplast and symplast. During the initial phase or apoplast, there is a rapid uptake of nutrients from the soil into the free spaces of plant cells. This process is passive and it usually occurs through trans-membrane proteins and ion-channels. In the second phase or symplast, the ions are taken slowly into the inner spaces of the cells. This pathway g...
Read More →Why do elements in the same group have similar physical and chemical properties?
Question: Why do elements in the same group have similar physical and chemical properties? Solution: The physical and chemical properties of elements depend on the number of valence electrons. Elements present in the same group have the same number of valence electrons. Therefore, elements present in the same group have similar physical and chemical properties....
Read More →What are gums made of? Is Fevicol different?
[question] Question. What are gums made of? Is Fevicol different? [/question] [solution] Solution: Gums are hetero-polysaccharides. They are made from two or more different types of monosaccharides. On the other hand, fevicol is polyvinyl alcohol (PVA) glue. It is not a polysaccharide. [/solution]...
Read More →How are the minerals absorbed by the plants?
Question: How are the minerals absorbed by the plants? Solution: The absorption ofsoil nutrients by the roots of plants occurs in two main phases apoplast and symplast. During the initial phase or apoplast, there is a rapid uptake of nutrients from the soil into the free spaces of plant cells. This process is passive and it usually occurs through trans-membrane proteins and ion-channels. In the second phase or symplast, the ions are taken slowly into the inner spaces of the cells. This pathway g...
Read More →Why is that in certain plants deficiency symptoms
Question: Why is that in certain plants deficiency symptoms appear first in younger parts of the plant while in others they do so in mature organs? Solution: Deficiency symptoms are morphological changes in plants, indicating nutrient deficiency. Deficiency symptoms vary from one element to another. The plant part in which a deficiency symptom occurs depends on the mobility of the deficient element in the plant. Elements such as nitrogen, potassium, and magnesium are highly mobile. These element...
Read More →Which element do you think would have been named by
Question: Which element do you think would have been named by (i) Lawrence Berkeley Laboratory (ii) Seaborgs group? Solution: (i) Lawrencium (Lr) with $Z=103$ and Berkelium (Bk) with $Z=97$ (ii) Seaborgium (Sg) with Z = 106...
Read More →Two discs of moments of inertia I1 and I2 about their respective axes
Question: Two discs of moments of inertia $I_{1}$ and $I_{2}$ about their respective axes (normal to the disc and passing through the centre), and rotating with angular speeds $\omega_{1}$ and $\omega_{2}$ are brought into contact face to face with their axes of rotation coincident. (a) What is the angular speed of the two-disc system? (b) Show that the kinetic energy of the combined system is less than the sum of the initial kinetic energies of the two discs. How do you account for this loss in...
Read More →If a plant shows a symptom which could develop due to deficiency of more than one nutrient, how would you find out experimentally,
Question: If a plant shows a symptom which could develop due to deficiency of more than one nutrient, how would you find out experimentally, the real deficient mineral element? Solution: In plants, the deficiency of a nutrient can cause multiple symptoms. For example, the deficiency of nitrogen causes chlorosis and delayed flowering. In a similar way, the deficiency of a nutrient can cause the same symptom as that caused by the deficiency of another nutrient. For example, necrosis is caused by t...
Read More →Write the atomic number of the element present in the third period
Question: Write the atomic number of the element present in the third period and seventeenth group of the periodic table. Solution: There are two elements in the $1^{\text {st }}$ period and eight elements in the $2^{\text {nd }}$ period., The third period starts with the element with $Z=11$. Now, there are eight elements in the third period. Thus, the $3^{\text {rd }}$ period ends with the element with $Z=18$ i.e., the element in the $18^{\text {th }}$ group of the third period has $Z=18$. Henc...
Read More →Draw the structure of the amino acid, alanine.
[question] Question. Draw the structure of the amino acid, alanine. [/question] [solution] Solution: Structure of alanine [/solution]...
Read More →In terms of period and group where would you locate the element
Question: In terms of period and group where would you locate the element withZ=114? Solution: Elements with atomic numbers from $Z=87$ to $Z=114$ are present in the $7^{\text {th }}$ period of the periodic table. Thus, the element with $Z=114$ is present in the $7^{\text {th }}$ period of the periodic table. In the $7^{\text {th }}$ period, first two elements with $Z=87$ and $Z=88$ are $s$-block elements, the next 14 elements excluding $Z=89$ i.e., those with $Z=90-103$ are $f-$ block elements,...
Read More →Name at least five different deficiency symptoms in plants. Describe them and correlate them with the concerned mineral deficiency.
Question: Name at least five different deficiency symptoms in plants. Describe them and correlate them with the concerned mineral deficiency. Solution: The five main deficiency symptoms arising in plants are: Chlorosis Necrosis Inhibition of cell division Delayed flowering Stunted plant growth Chlorosis or loss of chlorophyll leads to the yellowing of leaves. It is caused by the deficiencies of nitrogen, potassium, magnesium, sulphur, iron, manganese, zinc, and molybdenum. Necrosis is the death ...
Read More →Name at least five different deficiency symptoms in plants.
Question: Name at least five different deficiency symptoms in plants. Describe them and correlate them with the concerned mineral deficiency. Solution: The five main deficiency symptoms arising in plants are: Chlorosis Necrosis Inhibition of cell division Delayed flowering Stunted plant growth Chlorosis or loss of chlorophyll leads to the yellowing of leaves. It is caused by the deficiencies of nitrogen, potassium, magnesium, sulphur, iron, manganese, zinc, and molybdenum. Necrosis is the death ...
Read More →On the basis of quantum numbers, justify that the sixth period of
Question: On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements. Solution: In the periodic table of the elements, a period indicates the value of the principal quantum number (n) for the outermost shells. Each period begins with the filling of principal quantum number (n). The value ofnfor the sixth period is 6. Forn= 6, azimuthal quantum number (l) can have values of 0, 1, 2, 3, 4. According to Aufbaus principle, electrons are added to diff...
Read More →Explain with examples: macronutrients,
Question: Explain with examples: macronutrients, micronutrients, beneficial nutrients, toxic elements and essential elements. Solution: Macronutrients:They are the nutrients required by plants in large amounts. They are present in plant tissues in amounts more than 10 mmole kg1of dry matter. Examples include hydrogen, oxygen, and nitrogen. Micronutrients:They are also called trace elements and are present in plant bodies in very small amounts, i.e., amounts less than 10 mmole kg 1of dry matter. ...
Read More →What is the basic difference in approach between the Mendeleev’s
Question: What is the basic difference in approach between the Mendeleevs Periodic Law and the Modern Periodic Law? Solution: Mendeleevs Periodic Law states that the physical and chemical properties of elements are periodic functions of their atomic weights. On the other hand, the Modern periodic Law states that the physical and chemical properties of elements are periodic functions of their atomic numbers....
Read More →Attempt titrating an amino acid against a weak base and discover
[question] Question. Attempt titrating an amino acid against a weak base and discover the number of dissociating ( ionizable ) functional groups in the amino acid. [/question] [solution] Solution: Titrating a neutral or basic amino acid against a weak base will dissociate only one functional group, whereas titration between acidic amino acid and a weak acid will dissociate two or more functional groups. [/solution]...
Read More →Why is purification of water and nutrient salts so important in studies involving mineral nutrition using hydroponics?
Question: Why is purification of water and nutrient salts so important in studies involving mineral nutrition using hydroponics? Solution: Hydroponics is the art of growing plants ina nutrient solution in the absence of soil. Since the plant roots are exposed to a limited amount of the solution, there are chances that the concentrations of oxygen and other minerals in the plant roots would reduce. Therefore, in studies involving mineral nutrition using hydroponics, purification of water and nutr...
Read More →Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that?
Question: Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that? Solution: Mendeleev arranged the elements in his periodic table ordered by atomic weight or mass. He arranged the elements in periods and groups in order of their increasing atomic weight. He placed the elements with similar properties in the same group. However, he did not stick to this arrangement for long. He found out that if the elements were arranged strictly in ord...
Read More →A bullet of mass 10 g and speed 500 m/s is fired into a door and gets embedded exactly at the centre of the door.
Question: A bullet of mass 10 g and speed 500 m/s is fired into a door and gets embedded exactly at the centre of the door. The door is 1.0 m wide and weighs 12 kg. It is hinged at one end and rotates about a vertical axis practically without friction. Find the angular speed of the door just after the bullet embeds into it. (Hint: The moment of inertia of the door about the vertical axis at one end is $M L^{2} / 3$.) Solution: Mass of the bullet, $m=10 \mathrm{~g}=10 \times 10^{-3} \mathrm{~kg}$...
Read More →‘All elements that are present in a plant need not be essential to its survival’. Comment.
Question: All elements that are present in a plant need not be essential to its survival. Comment. Solution: Plants tend to absorb different kinds of nutrients from soil. However, a nutrientis inessential for a plantif it is not involved in the plants physiology and metabolism. For example, plants growing near radioactive sites tend to accumulate radioactive metals. Similarly, gold and selenium get accumulated in plants growing near mining sites. However, this does not mean that radioactive meta...
Read More →What is the basic theme of organisation in the periodic table?
Question: What is the basic theme of organisation in the periodic table? Solution: The basic theme of organisation of elements in the periodic table is to classify the elements in periods and groups according to their properties. This arrangement makes the study of elements and their compounds simple and systematic. In the periodic table, elements with similar properties are placed in the same group....
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