Biology Test-9

Fe and Mg minerals are required by plants for chlorophyll synthesis.

For the synthesis of chlorophyll in plants, the elements needed are iron and magnesium. Chlorophyll is an important component of the process of photosynthesis, which is the process by which light energy from the sun is converted to chemical energy to be utilized by the plants for growth. The light is absorbed by chlorophyll present in the plant.

Magnesium is a mobile and essential element that is important for the growth and development of a plant. It forms an integral component of the chlorophyll. It is the central component of chlorophyll, around which there is a nitrogen-containing porphyrin ring. Since magnesium is an essential part of the structure, it is highly needed for the synthesis of chlorophyll.

Iron is an important element as it is required for the formation of chlorophyll in plants. It also plays a role in maintaining the structural integrity of chloroplast, the structure within which chlorophyll is present.

Chlorophyll also has medicinal uses – detoxification, wound healing, reducing bad breath, and treating constipation. Iron and magnesium are the elements that are required for the synthesis of chlorophyll in plants.

Merocrine are the glands referred to as when secretary granules leave cells by exocytosis with no loss of other cellular material.

Merocrine (or eccrine) is a term used to classify exocrine glands and their secretions in the study of histology. A cell is classified as merocrine if the secretions of that cell are excreted via exocytosis from secretory cells into an epithelial-walled duct or ducts and then onto a bodily surface or into the lumen.

Links between organisms that show branching pattern of evolutionary relationships are shown by phylogenetic tree.

A phylogenetic tree is a diagram that represents evolutionary relationships among organisms. The pattern of branching in a phylogenetic tree reflects how species or other groups evolved from a series of common ancestors.

NPP = GPP - Plant respiration is correct about GPP and NPP in a ecosystem.

In a food chain, energy stored at the producer level is called as Primary Productivity (PP). Energy stored at the consumer level is called as secondary productivity. It is the rate of energy storage at the consumer level. Consumer-level includes herbivores, carnivores and decomposers. Gross Primary Productivity (GPP) is the rate of photosynthesis. Net Primary Productivity (NPP) is the rate of storage of organic matter except which is utilized for the respiration by plants. Hence, we can say that NPP = GPP - plant respiration. It is the total biomass available for consumers.

The number of contrasting characters studied by Mendel for his experiments was seven.

Seven pairs of contrasting characters in pea plants were studied by Mendel in his experiments. They were : i) form of seed; ii) colour of cotyledons; iii) colour of seed coat; iv) form of pod;  v) colour of pod; vi) position of flower; vii) height of plant (length of stem).

The minimum number of meiotic divisions required to obtain 100 pollen grain of wheat is 25.

During sexual reproduction in angiosperms, meiosis occurs in microspore and megaspore mother cells. In one meiotic division, one microspore mother cell in the anther forms 4 microspores, each of which develops as a pollen grain. When there are 100 pollen grains, the meiotic divisions which will be required are \(\frac{100}{4}\) \(=25\). The number of meiotic divisions for 100 pollen grains is 25.

The common fungicide used in preventing growth of fungus on herbarium specimens is mercuric chloride.

It is highly toxic compound that volatilizes slightly at ordinary temperature and appreciably at 100 degrees Celsius. Mercuric chloride is corrosive to mucous membranes and used as a topical antiseptic and disinfectant.

Genetic Engineering Appraisal Committee (GEAC) is the apex body for approval of genetically modified crops in India.

The Genetic Engineering Appraisal Committee (GEAC) is the apex body that allows for commercial release of GM crops. In 2002, the Genetic Engineering Appraisal Committee (GEAC) had allowed the commercial release of Bt cotton. More than 95 percent of the country's cotton area has since then come under Bt cotton.

Statins produced monascus purpureus microbes is commercialised as blood-cholesterol lowering agents.

Monascus purpureus is used to produce statin. Statins lower the blood cholesterol level by competitively inhibiting the enzyme responsible for the synthesis of cholesterol. Statins are bioactive molecules, produced by the yeast monascus purpureus. These bioactive molecules have been commercialized as blood-cholesterol lowering agents. It acts by competitively inhibiting the enzyme responsible for the synthesis of cholesterol.

The pulmonary alveoli are the terminal ends of the respiratory tree, which are the gas exchange sites. The alveolar membrane is the gas exchange surface. Carbon dioxide rich blood is pumped from the rest of the body into the alveolar blood vessels where, through diffusion, it releases its carbon dioxide and absorbs oxygen.

46 is the number of chromosomes in primary spermatocyte of human.

Spermatocytes are a type of male gametocytes in human. There are two types of spermatocytes: primary spermatocytes and secondary spermatocytes. Primary spermatocytes are diploid cells which consist of 46 chromosomes in each cell. Each secondary spermatocyte contains 23 chromosomes because they are haploid cells.

Carbon dioxide is primarily called a greenhouse gas because it traps heat.

An increase in the percentage of such gases in the atmosphere that would cause the average temperatures to increase world-wide and this is called the greenhouse effect. Carbon dioxide is one of the greenhouse gases. It is transparent to sunlight but traps the heat produced and keeps the surface of earth warm.

The stomatal aperture is surrounded by guard cells and widens (opens) when guard cells are turgid.

The kidney-shaped cells surrounding each stoma are guard cells. They regulate the rate of transpiration by opening and closing the stomata. When the guard cells are turgid, or swollen, the stomatal opening is large/widened. This turgidity is due to the accumulation of K+ ions. Potassium ions move into the vacuoles. The water moves into the vacuoles, following potassium ions. As a result, the guard cells expand and the stoma opens/widens.

At the end of first meiotic division, male germ cell differentiates into secondary spermatocyte.

During meiosis-I, primary spermatocyte is the main germ cell. It is diploid, (2n) with 44 + XY (total 46) chromosomes. It completes the first meiotic division (reduction division) leading to the formation of two equal, haploid cells called secondary spermatocytes, which have only 23 chromosomes each i.e., 22 + X or 22+ Y. So, at the end of first meiotic division, male germ cell differentiates into secondary spermatocyte.

Conversion of milk to curd improves its nutritional value by increasing the amount of Vitamin B₁₂.

Lactobacillus species are used as the starter for the conversion of the milk into curd. This bacteria helps in the conversion and also produces some nutrients and lactic acid. The bacteria helps in increasing the nutritional quality of vitamin B₁₂.