Q.Give a comparison between the behaviour of chromosomes and genes according to Mendel. OR How did natural selection affect the population of moth (in England)? Briefly explain.

Chromosome shape depends on centromere position: metacentric = V-shaped, submetacentric = L-shaped, acrocentric = J-shaped, telocentric = I/rod-shaped. Among the given options, (c) is the one that correctly anchors metacentric → V-shaped (iv-a) and acrocentric → J-shaped (ii-c).

Standard classification by centromere position (as they appear when pulled at anaphase):

• Metacentric (centromere in the middle, equal arms) → V-shaped.
• Submetacentric (centromere slightly off-centre, unequal arms) → L-shaped.
• Acrocentric (centromere near one end, one very short arm) → J-shaped.
• Telocentric (centromere terminal, single arm) → I / rod-shaped. …

Walter Sutton and Theodor Boveri proposed the chromosomal theory of inheritance.

Around 1902, Walter Sutton and Theodor Boveri independently recognised that the behaviour of chromosomes during meiosis exactly parallels the behaviour of Mendel's factors:

• Chromosomes (like factors) occur in pairs and segregate during gamete formation, then combine at fertilisation. …

Sutton and Boveri (1902) independently noted the parallel behaviour of chromosomes and Mendelian factors, giving the chromosomal theory of inheritance.

Walter Sutton and Theodor Boveri observed that the behaviour of chromosomes during meiosis (segregation and independent assortment) paralleled the behaviour of Mendel's factors (genes) — chromosomes occur in pairs, segregate during gamete formation, and are restored on fertilisation, exactly as Mendelian factors do. This led them to propose that genes are located …

The chromosomal theory of inheritance, linking Mendel's factors (genes) to the physical behaviour of chromosomes during meiosis, was proposed by Sutton and Boveri and experimentally validated by T.H. Morgan.

The chromosomal theory of inheritance

After the rediscovery of Mendel's laws in 1900, cytologists noticed striking parallels between the behaviour of Mendel's "factors" (genes) during inheritance and the behaviour of chromosomes during meiosis (e.g., chromosomes occur in pairs, segregate during meiosis, and are transmitted to offspring in a manner paralleling Mendel's law of segregation and independent assortment).

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The blank is Walter Sutton; Sutton and Boveri together proposed that chromosomes are the physical carriers of Mendelian factors (genes).

After the rediscovery of Mendel's work in 1900, cytologists noticed a striking parallel: chromosomes, like Mendelian 'factors', occur in pairs, segregate during meiosis (so that each gamete gets one member of a pair), and the pairs assort independently of each other. Working independently but publishing around the same time, Walter Sutton (an American cytologist) and Theodore Boveri (a German biologist) integrated these cytological observations with Mendelian principles and proposed that chromosomes are the vehicles of hereditary information — the genes …

The centromere joins the sister chromatids and carries the kinetochore for spindle-fibre attachment, ensuring correct chromosome segregation during mitosis/meiosis.

The centromere is the constricted (primary constriction) region of a chromosome where the two sister chromatids are held together. Its functions:

• It keeps the sister chromatids joined until they are separated during cell division.
• It bears a disc-shaped protein structure, the kinetochore, to which the spindle fibres (microtubules) attach. …