Evolution — NEET UG practice

1. First, recall which types of evidence are considered strong, reliable support for evolution by common descent.

2. Divergent evolution of anatomical structures such as forelimbs produces homologous organs, which share a common structural origin/ancestry — this directly supports the idea of common ancestry, so it is valid evidence for evolution.

3. Paleontological evidence from fossil records allows scientists to study organisms from different geological time periods, directly tracing evolutionary change over time — this is valid evidence for evolution.

4. Convergent evolution of traits like wings of birds and butterflies, however, produces analogous organs — structures that appear similar simply because unrelated species independently adapted to similar needs, without sharing a common ancestor. Since this doesn't demonstrate shared ancestry, it does not serve as evidence for evolution in the same way.

5. Embryological support for evolution as proposed by Ernst Haeckel (the idea that "ontogeny repeats phylogeny," based on observed similarities in early vertebrate embryos) was later disapproved after careful study by Karl Ernst von Baer, who showed that embryonic similarities don't hold up as strongly as originally claimed — so this is not valid/accepted evidence for evolution.

6. Hence, the answer is B, D.

1. Recall the accepted chronological sequence of human evolution, based on fossil evidence, from the earliest ancestor to modern humans.

The correct order is:

Ramapithecus → Australopithecines → Homo habilis → Homo erectus → Neanderthalensis → Homo sapiens

2. Now compare each option against this known sequence.

Only the option that places Ramapithecus first, followed by Homo habilis, then Homo erectus, then Neanderthal, and finally Homo sapiens, matches the correct order (skipping Australopithecines, which isn't listed as an option here but the relative order of the given species is still preserved).

3. Hence, the answer is A. Ramapithecus → Homo habilis → Homo erectus → Neanderthal → Homo sapiens.

1. First, recall that natural selection acts on the variation already present in a population and can push the population's traits in different directions depending on which individuals survive and reproduce more.

2. Check each listed outcome:

• Stabilisation: when individuals with average/intermediate traits are favoured over extreme traits, the population stabilises around the mean. This is a result of natural selection.
• Directional change: when one extreme of a trait is favoured, the population's trait distribution shifts in that direction over generations. This is a result of natural selection.
• Disruption: when both extreme traits are favoured over the intermediate one, the population splits into two distinct groups. This is also a result of natural selection.
• Genetic drift: this is a separate, random mechanism of evolution caused by chance events (like sampling error in small populations), not a directed outcome of natural selection.

3. Since stabilisation, directional change, and disruption are all outcomes that arise directly from natural selection acting on variation, while genetic drift is an independent random process, only (a), (c), and (d) qualify.

4. Hence, the answer is C. (a), (c) and (d) only.