Q24 of 27 Page 1

(a) In a pond, there were 200 frogs. 40 more were born in the year. Calculate the birth rate of the population.

(b) Population in terms of number is not always a necessary parameter to measure population density. Justify with two examples.

(a) Birth rate = a number of frogs added to the population in a given time/ total number of frogs initially present in the pond.

Birth rate = 40/200= 0.2 offspring per frog per year.


(b) Population in terms of number need not support all cases. If the population is huge and counting is impossible and time-consuming. For example:


• Consider an area with 200 parthenium plants and a single huge banyan tree. Even if the population density of the banyan tree is comparatively lower than Parthenium plants; the role played by a single banyan tree is much greater. In such case per cent cover or biomass is the best way to measure population size.


• Consider a petri dish with a culture of bacteria in a laboratory. Its impossible to take the count of bacteria and hence calculating absolute or relative population densities is the best way to determine the population size.


More from this chapter

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22

A 17-year old boy is suffering from high fever with profuse sweating and chills. Choose the correct option from the following diseases which explains these symptoms and rule out the rest with adequate reasons.

(a) Typhoid (b) Viral Fever (c) Malaria

 23

Study the given pedigree chart and answer the questions that follow:


(a) Is the trait recessive or dominant?


(b) Is the trait sex-linked or autosomal?


(c) Give the genotypes of the parents shown in generation I and their third child shown in generation II and the first grandchild shown in generation III.


OR


Haemophilia is a sex-linked recessive disorder of humans. The pedigree chart given below shows the inheritance of Haemophilia in one family. Study the pattern of inheritance and answer the questions given.


pedigree.png


(a) Give all the possible genotypes of the members 4, 5 and 6 in the pedigree chart.


(b) A blood test shows that the individual 14 is a carrier of haemophilia. The member numbered 15 has recently married the member numbered 14. What is the probability that their first child will be a haemophilic male.? Show with the help of Punnett square.

 25

People living in the coastal areas are forced to evict their dwelling units as the sea has inundated into the land areas. State the possible reasons and suggest measures that could be taken to reduce the deleterious changes in the environment.

OR


A young sperm whale, 33-foot long was found dead off the coast. It had a large amount of human trash like trash bags, polypropylene sacks, ropes, net segments etc. amounting to 29 kilograms in its digestive system. The whale died because of inflammation of the abdominal lining. Analyze the possible reasons for such mishaps and suggest measures that can be taken to reduce such incidents.

 26

Aneuploidy of chromosomes in human beings results in certain disorders. Draw out the possibilities of the karyotype in common disorders of this kind in human beings and its consequences in individuals.

OR


In a dihybrid cross, white-eyed, yellow bodied female Drosophila was crossed with red-eyed, brown bodied male Drosophila. The cross produced 1.3 per cent recombinants and 98.7 progeny with parental type combinations in the F2 generation. Analyze the above observation and compare with the Mendelian dihybrid cross.