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Question 1: Group the following as nitrogenous bases and nucleosides: Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine. Answer: Nitrogenous bases present in the list are adenine, thymine, uracil, and cytosine. Nucleosides present in the list are cytidine and guanosine. Question 2: If a double stranded DNA has 20 per cent of cytosine, calculate the per […]

Question 1: Mention the advantages of selecting pea plant for experiment by Mendel. Answer: Mendel selected pea plants to carry out his study on the inheritance of characters from parents to offspring. He selected a pea plant because of the following features. (a) Peas have many visible contrasting characters such as tall/dwarf plants, round/wrinkled seeds, green/yellow

Question 1: What do you think is the significance of reproductive health in a society? Answer: Reproductive health is the total well being in all aspects of reproduction. It includes physical, emotional, behavioural, and social well being. Sexually transmitted diseases such as AIDS, gonorrhoea, etc. are transferred from one individual to another through sexual contact.

Question 1: Fill in the blanks: (a) Humans reproduce __________. (asexually/sexually) (b) Humans are__________. (oviparous/viviparous/ovoviviparous) (c) Fertilization is __________ in humans. (external/internal) (d) Male and female gametes are __________. (diploid/haploid) (e) Zygote is __________. (diploid/haploid) (f) The process of release of the ovum from a mature follicle is called__________. (g) Ovulation is induced by a hormone called the __________. (h) The fusion of

Question 1: Name the parts of an angiosperm flower in which development of male and female gametophyte take place. Answer: The male gametophyte or the pollen grain develops inside the pollen chamber of the anther, whereas the female gametophyte (also known as the embryo sac) develops inside the nucellus of the ovule from the functional

Question 1: Why is reproduction essential for organisms? Answer: Reproduction is a fundamental feature of all living organisms. It is a biological process through which living organisms produce offspring’s similar to them. Reproduction ensures the continuance of various species on the Earth. In the absence of reproduction, the species will not be able to exist

Question 16.1: Sleeping pills are recommended by doctors to the patients suffering from sleeplessness but it is not advisable to take its doses without consultation with the doctor, Why? Answer: Most drugs when taken in doses higher than recommended may cause harmful effects and sometimes, may even lead to death. Hence, a doctor should always

Question 15.1: What are polymers? Answer: Polymers are high molecular mass macromolecules, which consist of repeating structural units derived from monomers. Polymers have a high molecular mass (103 − 107 u). In a polymer, various monomer units are joined by strong covalent bonds. These polymers can be natural as well as synthetic. Polythene, rubber, and nylon 6,

Question 14.1: Glucose or sucrose are soluble in water but cyclohexane or benzene (simple six membered ring compounds) are insoluble in water. Explain. Answer: A glucose molecule contains five −OH groups while a sucrose molecule contains eight −OH groups. Thus, glucose and sucrose undergo extensive H-bonding with water. Hence, these are soluble in water. But

Question 13.1: Classify the following amines as primary, secondary or tertiary: (i) (ii) (iii) (C2H5)2CHNH2 (iv) (C2H5)2NH   Answer: Primary: (i) and (iii) Secondary: (iv) Tertiary: (ii) Question 13.2: (i) Write structures of different isomeric amines corresponding to the molecular formula, C4H11N (ii) Write IUPAC names of all the isomers. (iii) What type of isomerism is exhibited by different pairs of amines? Answer: (i), (ii) The