Chapter 14: Ecosystem
1. Fill in the blanks.(a) Plants are called as————- because they fix carbon dioxide.(b) In an ecosystem dominated by trees, the pyramid (of numbers) is————- type.(c) In aquatic ecosystems, the limiting factor for the productivity is————- .(d)…
Chapter 15: Biodiversity and Conservation
1. Name the three important components of biodiversity.Ans: Three components of biodiversity are:(a) Genetic diversity(b) Species diversity(c) Ecological diversity 2. How do ecologists estimate the total number of species present in the world?Ans: Ecologists estimate the total number of…
Chapter 16: Environmental Issues
1. What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.Ans: Domestic sewage contains four kind of impurities:(i) Suspended solids: They are soil particles such as sand and silt.(ii) Colloidal particles: They are…
Chapter 3: Biology Human Reproduction
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 ovum from a mature follicle is called————— .(g)Ovulation is induced by a hormone…
Chapter 4: Reproductive Health
1. What do you think is the significance of reproductive health in a society?Ans: Reproductive health in a society is significant because the people are aware of(i) birth control methods and advantages of small family,(ii) sexually transmitted diseases…
Chapter 5: Principles of Inheritance and Variation
1.Mention the advantages of selecting pea plant for experiment by MendelAns: Mendel select garden pea (Pisum Sativum) for the following reasons.(i) It is an annual plant with short life span and gives results within 3 months.(ii) The plant…
Chapter 6: Molecular Basis of Inheritance
1. Group the following as nitrogenous bases and nucleosides: Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine.Ans: Nitrogenous Bases – Adenine, Uracil and Cytosine, Thymine; Nucleosides – Cytidine, guanosine. 2. If a double stranded DNA has 20 per cent…
Chapter 7: Evolution
Evolution Chapter Class 12 NCERT Q1. Explain antibiotic, resistance observed in bacteria in light of Darwinian selection theory.Ans: According to Darwin, environment selects organisms with favourable variations and these organisms are allowed to survive. When a bacterial population…
Chapter 8: Human Health and Disease
1.What are the various public health measures, which you would suggest as safeguard against infectious diseases?Ans. The various public health measures against infectious diseases includes the following –1.Education – People should be educated about the infectious diseases so that…
Chapter 9: Strategies for Enhancement in Food Production
1. Explain in brief the role of animal husbandry in human welfare.Ans: Animal husbandry deals with the caring, feeding and management of domesticated animals. It includes poultry, farming and fisheries.These animals are very useful for human beings…
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