Sindh Mdcat Exclusive Course Biology Evolution — Solved MCQs

Question 1

Many scientists believe that one of the following is evolutionary origin(s) of animals, plants and fungi?

Accepted Answer

C. Bacteria — The evolutionary organism believed by bacteria in early evolutionary sequence via various chemicals is bacteria. They believe that bacteria is formed as the origin of animals, plants, and fungi.These bacteria are found thriving on all the above animals, plants, and fungi. The bacteria contain the smallest DNA with 160000 base pairs. They are often used for research purposes and also for evolution studies for enhanced knowledge.

Question 2

According to the theory of natural selection, organisms produce:

Accepted Answer

D. More offspring than the environment can support — According to the theory of natural selection, organisms produce more offspring than the environment can support. This overproduction leads to competition for limited resources. Those offspring with advantageous traits are more likely to survive and reproduce, thus propagating favorable traits through generations, driving evolution. This makes option D correct.Option A is incorrect because it suggests that offspring numbers are adjusted to match resources, which contradicts the principle of overproduction intrinsic to natural selection.Option B is incorrect as it implies a resource management goal, which is not a concept in natural selection.Option C is incorrect because it suggests offspring are produced to increase resources, which does not align with the theory of natural selection focusing on survival and adaptation within existing resources.

Question 3

Consider the following statements about biological communities.I. Their members share a common gene poolII. The community remains stable even though some physical aspect of the environment may undergo a changeIII. It consists of all the populations living in a particular area.IV. A community interacts with a non-living environment and both function together to form an ecosystemWhich two of the above statements are true?

Accepted Answer

E. 3 and 4 — Different living and nonliving things in a single habitat form a single community. Since different species are present they have different characteristics so the gene pool is not the same. Change in the environment does cause a change in the balance of genes in the environment so the community does not remain stable.The last two statements iii and iv are right that as previously mentioned the community is all the population living in a particular area. Secondly, the community involves biotic(living) and abiotic(non-living) factors interacting with one another.

Question 4

Population growth is checked by which of the following?

Accepted Answer

D. Competition — Competition is the correct answer because it serves as a natural mechanism for controlling population growth. When individuals compete for limited resources such as food, water, and habitat, only the most adapted survive and reproduce. This keeps the population in check and maintains ecological balance. In contrast, 'No competition' would lead to unregulated population expansion, while 'No polymorphism' and 'Polymorphism' relate to genetic diversity, affecting adaptability rather than directly regulating population growth.

Question 5

Which of the following is not a vestigial organ of man?

Accepted Answer

D. None of these — Vestigial structures are anatomical remnants that were important in the organism's ancestors but are no longer needed in the same capacity. In humans, the appendix and coccyx are typically considered vestigial. The appendix may have once helped in digestion, while the coccyx is the remnant of a tail. Therefore, 'None of these' is the correct answer because both the appendix and coccyx are vestigial organs. Options A, B, and C incorrectly suggest that one or both of these organs are not vestigial.

Question 6

Two species can avoid competition and better use the environment's resources by occupying different:

Accepted Answer

C. Niches — The correct answer is niches. A niche encompasses the role a species plays in its ecosystem, including how it acquires resources, survives, and reproduces. By occupying different niches, species can coexist in the same environment without direct competition, allowing each to exploit different resources and conditions effectively.Adaptations are about traits enhancing survival and reproduction but do not specifically address interspecies competition. Polymorphism refers to genetic diversity within a species and does not relate to the interaction between species. Specialization allows species to focus on specific roles, but it is more about within-species adaptation rather than interspecific niche differentiation.

Question 7

There is a small population of beetles on grass in which some are green and some are brown in color. A group of students is passing from that place and walks on them. By chance, green color beetles are pressed under their feet resulting in:

Accepted Answer

C. Change in the genetic equilibrium of that population — The genetic equilibrium of the population will be affected because green beetles can camouflage with green grass and as a result can be pressed under the feet more often than brown beetles. This will disbalance the ratio of the brown allele to green allele, as the number of green alleles will decrease.

Question 8

In the Hardy - Weinberg principle, p2 + 2pq + q2 = 1. q2 represents the frequency of the:

Accepted Answer

D. Homozygous recessive — q2 represents the homozygous recessive trait in the Hardy-Weinberg principle.It is calculated by squaring the frequency of the recessive allele q, where q is the frequency of the recessive allele and p is the frequency of the dominant allele. The entire equation is p2+2pq+q2 where p2 is the homozygous dominant frequency and 2pq is the heterozygous frequency.

Question 9

Lamarck is best known for his theory of:

Accepted Answer

C. Inheritance of acquired characteristics — Lamarck is best known for his Theory of Inheritance of Acquired Characteristics, first presented in 1809 (Darwin's first book dealing with natural selection was published in 1859): If an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring.

Question 10

The wings of birds and the forelegs of a horse are _ structures.

Accepted Answer

B. Homologous — A great example of homologous structures is the wings of a bird and the forelegs of a horse. Birds and horses are both animals, so they share a common ancestry. Both a bird's wing and a horse’s foreleg share a similar internal bone structure, even though they look very different externally.

Question 11

Many scientists believe that one of the following is evolutionary origin of animals, plants and fungi?

Accepted Answer

C. Bacteria — Bacteria are considered one of the earliest and most primitive forms of life. They are believed to be the ancestors of all complex eukaryotic life forms, including plants, animals, and fungi, through a process of evolution that involved endosymbiosis and other mechanisms of genetic exchange. Protists, algae, and protozoans are all more complex forms of life that evolved later and are not considered the direct ancestors of plants, animals, and fungi.

Question 12

The organs which are similar in function but differ in structure are called:

Accepted Answer

A. Analogous organs — Analogous organs have a similar function but with different embryonic origins and structures. Homologous structures share a similar embryonic origin and but have the different functions. For example, the bones in a whale's front flipper are homologous to the bones in the human arm. However, a butterfly's or a bird's wings are analogous in comparison but not homologous.

Question 13

_ occurs because natural selection gives some alleles a better chance of survival than others:

Accepted Answer

B. Evolution — A mechanism of evolution in which allele frequencies of a population change over generations due to chance.Some chances favor more to a specific allele as compared to its counterparts,thus remains.Some variations make an individual better suited to survive and reproduce in their environment. Natural selection is a mechanism, or cause, of evolution.

Question 14

Key point to Lamarck's view about organic evolution is that every offspring

Accepted Answer

B. Inherits characters acquired by the parental generation — Lamarck's theory of organic evolution is centered on the idea that characteristics acquired during an organism's lifetime can be passed on to its offspring. This notion of 'inheritance of acquired characteristics' was Lamarck's key contribution to evolutionary thought. However, modern genetics, based on Mendelian principles and the role of DNA, does not support the inheritance of traits acquired during a parent's lifetime. Instead, genetic traits are passed down through DNA. The incorrect options either describe general truths about offspring or relate to concepts from other evolutionary theories, such as Darwin's natural selection or Haeckel's recapitulation theory.

Question 15

Whose theory of natural selection is essentially identical to Darwin’s theory?

Accepted Answer

B. Alfred Wallace — Alfred Wallace was a contemporary of Charles Darwin and independently arrived at the theory of natural selection. In 1858, Wallace sent a letter to Darwin outlining his ideas, which were remarkably similar to Darwin's theory. This letter, along with Darwin's own unpublished work, was presented to the Linnean Society of London in 1858.

Question 16

Natural selection can amplify or diminish variations that are?

Accepted Answer

A. Heritable — The correct answer is heritable. Natural selection acts on variations that are genetically encoded, allowing these traits to be passed down to future generations. This process can increase or decrease the prevalence of these traits in a population over time. Non-heritable and acquired traits do not have a genetic basis and, therefore, do not play a role in evolutionary processes driven by natural selection. Option B and D traits cannot be affected by natural selection, and Option C is incorrect because natural selection does not act on non-heritable traits.

Question 17

Homology means

Accepted Answer

D. Study of similar organs but with different functions — The correct answer is Option D: Homology is the study of similar organs or structures that arise from a common evolutionary ancestor, even if they have diverged to perform different functions. For instance, the forelimbs of humans, wings of birds, and flippers of whales are homologous structures. They share a common skeletal structure but have evolved to serve different functions. Option A is incorrect as it does not address the concept of homology. Option B is incorrect because it describes analogy, where features are similar due to convergent evolution rather than common ancestry. Option C is incorrect as it also describes analogy, focusing on functional similarity rather than structural similarity due to common descent.

Question 18

The ability of an individual to pass on its phenotype to future generations is known as:

Accepted Answer

B. Heritability — The correct answer is Option B: Heritability. Heritability refers to the proportion of observed variation in a particular trait that can be attributed to inherited genetic factors in a population. It is crucial in understanding the transmission of traits from parents to offspring. In contrast, Option A: Fitness describes an organism's reproductive success but does not focus on the genetic transmission of traits. Option C: Limited environmental resources discusses competition for resources rather than trait inheritance. Option D: Overproduction of offspring addresses reproductive strategies that lead to competition but does not involve genetic transmission. Lastly, Option E: Phenotypic variation describes the diversity of traits but does not encompass the mechanism of inheritance.

Question 19

The last common ancestor of humans is known to be which of the following?

Accepted Answer

D. Pan troglodytes — Chimpanzees (Pan troglodytes) are our closest living relatives. The evolutionary divergence between the human lineage and the Pan lineage, comprising chimpanzees and bonobos, occurred around 7 million years ago. This makes Pan troglodytes the correct answer. The other options, such as Homo neanderthalensis and Lemuroidea, represent distinct branches of the evolutionary tree that do not directly lead to modern humans. Dromaeosaurus is unrelated to the human evolutionary line as it is a dinosaur species.

Question 20

Catastrophism theory was given by:

Accepted Answer

A. Cuvier — The Catastrophism theory, given by George Cuvier, is a geologic theory that stipulates that the gaps in fossil records are due to several natural disasters like flooding which intermittently caused mass extinctions. Lamarck is best known for his theory of inheritance of acquired characteristics. The theory states that if an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring. Charles Darwin is best known for his theory of evolution which states that evolution happens by natural selection. James Hutton is known as the father of modern geology.

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