BIOLOGY ADVANCE QUESTION AND ANSWERS

 

QN 2.Liverworts and mosses have sometimes been described as the amphibians of the plant word. Briefly explain why this should be. Amphibians, like liverworts and mosses, are only partially adapted to life on land. 

ANS

Having bodies which easily lose water. They still rely on water for sexual reproduction. Both groups of organisms are thought by some scientists to represent intermediate stage in evolution. 

Qn 3.How are ferns better adopted to life on land than liverworts or mosses? 

ANS

The sporophyte has become adapted for life on land although the gametophyte depends on water for swimming gametes. The sporophyte generation has true vascular tissue and true roots stem and leave which to exploit the land environment more successfully. The sporophyte is the dominant generation the life of the gametophyte being short. The mature sporophyte is no longer dependent on the gametophyte. 

Qn 4.In what main respects are mosses, liverwort and ferns poorly adopted to life on land?

ANS

 Sexual reproduction is dependent on water since it involves free swimming sperm. The gametophyte thallus is susceptible to desiccation. The plant is often relatively intolerant of high light intensities.

 Qn 5The chance of survival and development of wind-blow pollen grains are much less than those of spores of Dryopteris.why? 

ANS

The dryopteris spores can develop wherever it falls, providing condition are moist and fertile, pollen grains must reach the female parts of the saprophyte. 

Qn 6 Cells of poikilothermic (cold-blooded) animals usually have a higher proportion of unsaturated fatty acid homoeothermic (warm-blooded) animalis.can you accounts for this?

ANS

 Body temperature of poikilothermic animals become lower in cold environment .lipids rich in unsaturated fatty acids (which have low melting points) generally remain liquid at temperature lower (usually5 oC or lower) than those rich in saturated fatty acids, This may be necessary if the lipids is to maintain its function, such as a constituents of membranes.

 Qn 7.A camel store fat in the hump primarily as water source rather than as an energy source. 

(a) By what metabolic process would water be made available from fat? 

(b) Carbohydrate could also be used as water source in the same process. what advantage does fat have over carbohydrate?

      ANS

 (a)Cell respiration (internal or tissue respiration).Fat undergoes oxidation 

(b)Only the hydrogen part of carbohydrate and fat molecules yields water on oxidation (2H2 + O2 2H2O) And fats contain relatively more hydrogen than carbohydrates on weight basis (nearly twice as much).