Assertion: Inheritance is the process by which genetic information is passed on from
parents to offspring
Reason: Inheritance is related to the fact that both father and mother contribute unequally
in the genetic material of the child. (1)
Q15. Assertion: Magnetic fields produced by current carrying circular coil are in form
of straight lines at the centre.
Reason: Magnetic field is non-uniform and parallel to the plane of the coil (1)
016. Assertion: Rings of cartilage are present in the throat.
Reason: These ensure that the air-passage does not collapse. (1)
17
Answers
Answer:
Explanation:
Perhaps the most fundamental property of all living things is the ability to reproduce. All organisms inherit the genetic information specifying their structure and function from their parents. Likewise, all cells arise from preexisting cells, so the genetic material must be replicated and passed from parent to progeny cell at each cell division. How genetic information is replicated and transmitted from cell to cell and organism to organism thus represents a question that is central to all of biology. Consequently, elucidation of the mechanisms of genetic transmission and identification of the genetic material as DNA were discoveries that formed the foundation of our current understanding of biology at the molecular level.
Go to:
Genes and Chromosomes
The classical principles of genetics were deduced by Gregor Mendel in 1865, on the basis of the results of breeding experiments with peas. Mendel studied the inheritance of a number of well-defined traits, such as seed color, and was able to deduce general rules for their transmission. In all cases, he could correctly interpret the observed patterns of inheritance by assuming that each trait is determined by a pair of inherited factors, which are now called genes. One gene copy (called an allele) specifying each trait is inherited from each parent. For example, breeding two strains of peas—one having yellow seeds, and the other green seeds—yields the following results (Figure 3.1). The parental strains each have two identical copies of the gene specifying yellow (Y) or green (y) seeds, respectively. The progeny plants are therefore hybrids, having inherited one gene for yellow seeds (Y) and one for green seeds (y). All these progeny plants (the first filial, or F1, generation) have yellow seeds, so yellow (Y) is said to be dominant and green (y) recessive. The genotype (genetic composition) of the F1 peas is thus Yy, and their phenotype (physical appearance) is yellow. If one F1 offspring is bred with another, giving rise to F2 progeny, the genes for yellow and green seeds segregate in a characteristic manner such that the ratio between F2 plants with yellow seeds and those with green seeds is 3:1.
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