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Solution for Class 12, Biology

Question 1

Oestrus cycle occurs in which of the following ?

Man
Monkey
Cow
All of these

Topic:

Human Physiology

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Question 2

Let us now focus on the first instance of the construction of an artificial recombinant DNA molecule. The construction of the first recombinant DNA emerged from the possibility of linking a gene encoding antibiotic resistance with a native plasmid (autonomously replicating circular extra-chromosomal DNA) of Salmonella typhimurium. Stanley Cohen and Herbert Boyer accomplished this in 1972 by isolating the antibiotic resistance gene by cutting out a piece of DNA from a plasmid which was responsible for conferring antibiotic resistance. The cutting of DNA at specific locations became possible with the discovery of the so-called

Topic:

Biotechnology

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Question 3

3. 4. MENSTRUAL CYCLE It is The reproductive cycle in the female prim human beings) is called menstrual cycle. at puberty and is called menarche. In hy is repeated at an average interval of about events starting from one menstruation

t

menstrual cycle. One ovum is released

Topic:

Human Physiology

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Question 4

Low

0 - R

patential favors the grop G microbrganis ms,

Aerobic
An a erobic
osmponilic
Haloplilic

Topic:

Biotechnology

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Question 5

In which of the following foods, the precence of partulin has been detected?

apple cider and apple juice
Wheat
Cheese
Rice flour.

Topic:

Biotechnology

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Question 6

In brtulism, the type of toxin secreted by bacteria is

Cxtotoxin
Enterrotoxin
Exotoxin
Neurotoxin

Topic:

Biotechnology

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Question 7

Question: Which one of the following elements in plants is not remobilised?

Phosphorus
Calcium
Potassium
Sulphur

Topic:

Plant Physiology

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Question 8

Which one of the following elements in plants is not remobilised?

Phosphorus
Calcium
Potassium
Sulphur

Topic:

Plant Physiology

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Question 9

Or, yellow cotyledon and wrinkled seed, green cotyledon we ratio in

F_{2}

generation, board. And also explain Genotype and Phenotype ratio in Q. 18. What is Ecological Succession? Write its various steps. Or,

Topic:

Ecology

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Question 10

The integration of natural science and organisms, cells, parts thereof, and molecular analogues for products and services'. 11. 1 PRINCIPLES OF BIOTECHNOLOGY

Topic:

Biotechnology

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Question 11

Q.8. What is the significance of histones in DNA packaging ? Ans. Histones are basic proteins. These proteins provide core to ac TA for winding/coiling. These proteins, thus help in making the struc

Topic:

Genetics and Evolution

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Question 12

Sir i want to confirm that young leaf mein photosyntheis jyaca hoga na?

Topic:

Plant Physiology

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Question 13

2.3.1 Phycomycetes (Algal (ungi) Members of phycomycetes are found in aquatic habitats and on decaying wood in moist and damp places or as obligate parasites on plants. The mycelium is aseptate and coenocytic. Asexual reproduction takes place by zoospores (motile) or by aplanospores (non-motile). These spores are endogenously produced in sporangium. A zygospore is formed by fusion of two gametes. These gametes are similar in morphology (isogamous) or dissimilar (anisogamous or oogamous) Some common examples are Mucor (Figure

2.5 a

), Rhizopus (the bread mould mentioned earlier) and Albugo (the parasitic fungi on mustard).

Topic:

Diversity in the Living World

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Question 14

Ghoeter

- 4

1. What are the measures one has to take to prevent: from contrac -ting STDS?

Topic:

Diversity in the Living World

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Question 15

Target : Pre-Medical 2020/02-12.2018 132. A short length of DNA contains 80 thymine and 80 guanine bases, then how many total N-bases will be present in this DNA?

Topic:

Cell: Structure and Functions

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Question 16

Action spectrum of photosynthesis resembles roughly the

Absorption spectrum of chlorophyll $a$
Absorption spectrum of chlorophyll $b$
Both (a) and (b)
Absorption spectrum of chlorophyll $c$

Topic:

Plant Physiology

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Question 17

Fig. Incomplete dominance in Mirabilis jala Q.5. Explain the chromosomal theory of linkage. Ans. Chromosomal theory of linkage was produced by main points of this hypothesis are : 1. Linked genes are found on a chromosome. 2. The strength of linkage depends upon the distance bet

Topic:

Genetics and Evolution

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Question 18

myosin. Both the proteins are arranged as rod-like structures, parallel to each other and also to the longitudinal axis of the myofbrils. Aetin filaments are thinner as compared to the myosin filaments, hence are commonly called thin and thick filaments respectively. In the centre of each 'I' band is an elastic fibre called 'Z line which bisects it. The thin filaments are firmly attached to the '

Z

line. The thick filaments in the 'A' band are also held together in the middle of this band by a thin flbrous membrane called 'M' line. The 'A' and 'T bands are arranged alternately throughout the length of the myofibrils. The portion of the myofibril between two successive '

Z

lines is considered as the functional unit of contraction and is called a sarcomere (Figure 20.2). In a resting state, the edges of thin fllaments on either side of the thick flaments partially overlap the free ends of the thick flaments leaving the central part of the thick filaments. This central part of thick filament, not overlapped by thin flaments is called the 'H' zone.

Topic:

Human Physiology

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Question 19

this lies the adrena(cortex)(Figure

22.4 b

). Underproduction of hormones by the adrenal cortex alter carbohydrate metabolism causing acute weakness and fatigue tead to a disease called Addison's disease.

Topic:

Human Physiology

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Question 20

Selection of recombinants due to inactivation of antibiotics is a cumbersome procedure because it requires simultaneous plating on two plates having different antibiotics. Therefore, alternative selectable markers have been developed which differentiate recombinants from non-recombinants on the basis of their ability to produce colour in the presence of a chromogenic substrate. In this, a recombinant DNA is inserted within the coding sequence of an enzyme,

β

-galactosidase. This results into inactivation of the gene for synthesis of this enzyme, which is referred to as insertional inactivation. The presence of a chromogenic substrate gives blue coloured colonies if the plasmid in the bacteria does not have an insert. Presence of insert results into insertional inactivation of the

β

-galactosidase gene and the colonies do not produce any colour. these are identified as recombinant colonies.

Topic:

Biotechnology

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Solution for Class 12, Biology

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