Explanation

A mature and duplicated chromosome consists of two identical double helix DNA molecules.

These two identical copies, called sister chromatids, are joined at a constricted region called the centromere. 

Explanation

The most primitive respiratory process occurring in a living cell is Glycolysis 

Glycolysis is an anaerobic process (does not require oxygen) that breaks down glucose into pyruvate.

It occurs in the cytoplasm of nearly all living cells

And is thought to be the earliest form of energy production that evolved in ancient, oxygen-free environments

Explanation

The main function of receiving, retaining, and nourishing a fertilized ovum is performed by the uterus. 

The fertilized ovum (zygote) travels to the uterus, where it implants in the uterine wall (endometrium) and develops into an embryo and then a fetus.

Explanation

Explanation

Explanation

Explanation

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Explanation

Self-fertilization in plants through successive generations leads to the development of True breeding plants. 

True breeding plants are those that consistently produce offspring with the same traits when self-fertilized.

This is because self-fertilization eliminates the introduction of new genetic material from another plant, ensuring that the offspring inherit the same genetic characteristics as the parent.

Over generations, this genetic uniformity becomes established within the population. 

Explanation

In a relaxed muscle fiber,  Tropomyosin blocks the myosin binding site on the thin filament, preventing the thick filaments from binding, thus preventing muscle contraction. 

Tropomyosin:

This protein sits on the actin filament and covers the myosin binding sites, effectively blocking them from interacting with myosin heads in a relaxed muscle. 

Role of Calcium:

When calcium ions are present, they bind to troponin, which then causes a conformational change in tropomyosin, exposing the myosin binding sites on actin, allowing for muscle contraction.