In the pedigree shown, individuals with the solid symbols suffer from a genetic disease caused by a recessive allele at an autosomal locus. You would counsel the couple marked A and B that the probability that each of their children will have the disease is:
In most ecosystems, the biomass of a trophic level is higher than the biomass of its predators, as illustrated below by an upright pyramid of biomass. In the open ocean, however, the biomass of primary producers (microscopic algae) is often lower than the biomass of higher trophic levels (for example, zooplankton and fish), as illustrated below by an inverted pyramid of biomass. In the open ocean, how can there be enough food to support the higher trophic levels?
A)
The microscopic primary producers are a source of food of high quality.
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B)
The microscopic primary producers have high rates of growth and reproduction.
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C)
The higher trophic levels are cold-blooded animals which do not require much food.
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D)
The higher trophic levels are efficient predators.
Refer the given graph showing hormonal secretions by the placenta during pregnancy. Which among the hormones X, Y and Z maintains corpus luteum and has properties similar to luteinizing hormone (LH) ?
A city was intensively sprayed with DDT in 1953 in an effort to control houseflies. The number of flies was immediately greatly reduced. Each year thereafter the city was again sprayed with DDT but the flies gradually increased in number until ten years later they were almost as abundant as they were when the control program began. Which one of the following is the most likely explanation?
A)
Flies from other areas moved in and replaced those killed by DDT
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B)
The few flies that were affected by DDT got survived and developed resistance to DDT which they passed on to their descendants
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C)
The DDT caused new mutations to occur in the surviving flies and this resulted in resistance to DDT
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D)
The DDT killed susceptible flies but the few that were naturally resistant lived and reproduced and their offspring repopulated the area
Corns with high and low sugar contents were selected and grown separately for the next 40 generations. The graph depicts the results of these lab experiments.
If the fossil record has few or no intermediate forms, if there are long periods in which the fossils underwent no morphological change, and if new forms arose very quickly, then evolution of these new forms would be best described as:
Performance of an organism with respect to the environmental conditions is shown below in graphs (I) and (II). A: reproduction, A + B: growth and A + B + C: survival Compare the two graphs. (Assume that both the graphs have identical X and Y axes). Select the correct interpretation.
A)
Species shown in graph (II) is more evolved and more specialised in function than that shown in graph (I).
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B)
Species shown in graph (II) has higher survivorship but less reproductive success.
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C)
Both species have identical feeding niche.
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D)
If both the species coexist, there are greater chances of (I) being eliminated due to severe competition.
The given figure illustrates a section of human ovary during the reproductive cycle. Which of the following statements most accurately describes each structure?
A)
The hormone produced by structure causes thing of the utherin cervical mucus to allow passage of sperm
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B)
During ovulation, structure stays at the interphase between meiosis I and meiosis II.
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C)
The hormone produced by structure stimulates the pituitary gland to secrete luteinizing hormone.
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D)
The hormo; produced by structure causes the proliferation of the uterine endometrium.