The cytochrome P450 constitute a superfamily of heme-containing enzymes that occur in nearly all living organisms, from bacteria to mammals, These monooxygenases, which in animals are embedded in the endoplasmic reticulum membrane, catalyze reactions of the sort

                  RH + O₂ + 2 H⁺ + 2e⁻ → ROH + H₂O 

The electrons (e−) are supplied by NADPH, which passes them to cytochrome P450’s heme prosthetic group via the intermediacy of the enzyme NADPH P450 reductase. Here RH represents a wide variety of usually lipophilic compounds for which the different cytochromes P450 are specific. They include

a. polycyclic aromatic hydrocarbons 

b. polycyclic biphenyls

c. frequently carcinogenic compounds that are present in tobacco smoke, broiled meats, and other pyrolysis products

d. which were widely used in electrical insulators and as plasticizers and are also carcinogenic.

#Question id: 11379

#Unit 10. Ecological Principles

Which of the following is NOT a prediction arising out of Wilson-MacArthur's -Theory of Island Biogeography?

#Question id: 11380

#Unit 10. Ecological Principles

Which of the following is/are NOT valid explanation(s) for the observed pattern of species richness?

#Question id: 11381

#Unit 10. Ecological Principles

Which of the following is decreasing order of NPP per unit area of different ecosystem?

#Question id: 11382

#Unit 10. Ecological Principles

Ecologist has proposed following explanation to lead biodiversity at tropic.

a) Higher productivity in the tropics allows for more species

b)  Environments are more stable and predictable in the tropics, with fairly constant temperatures and rainfall levels year-round

c) Predators and pathogens limit competition in the tropics, which allows more species to coexist

d) High evolutionary speed at tropic than temperate

#Question id: 11383

#Unit 10. Ecological Principles

Following some condition are given for island.

Island P is small and near the mainland;

Island Q is small and far from the mainland;

Island R is large and near the mainland;

Island S is large and far from the mainland

Let NP, NQ, NR and NS denote the number of species on islands P, Q, R and S, respectively. Which of the following is consistent with the theory of island biogeography?

#Question id: 11384

#Unit 10. Ecological Principles

Two islands, P and Q, are similar in habitat and other features. They are 100 and 200 km2 in size respectively, but have the same number of species. Which of the following statements can independently explain this observation?

(i) P is closer to the mainland than Q

(ii) P is further away from the mainland than Q

(iii) P has higher speciation rates than Q

(iv) P has lower speciation rates than Q