STD 12 - 7. human health and disease — NEET STD 11 Science — Question

At which stage of life the oogenesis process is initiated?

Natural selection in which more individuals acquire peripheral character value at both the ends of the distribution curve is

The convergent evolution of two species is usually associated with

Mechanism of muscle contraction is best explained by the sliding filament theory which states that contraction of a muscle fibre takes place by the sliding of the thin filaments over the thick filaments. Organise sequence of contraction and choose correct option :
(i) Action potential spreads through the muscle fibre and causes the release of calcium ions into the sarcoplasm.
(ii) This pulls the attached actin filaments towards the centre of A-band.
(iii) Utilising the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge.
(iv) Increase in Ca⁺⁺ level leads to the binding of calcium with a subunit of troponin on actin filaments and thereby remove the masking of active sites for myosin.
(v) Signal sent by the central nervous system (CNS) via a motor neuron.
(vi) The Z-line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction.
(vii) A neural signal reaching neuromuscular junction releases a neurotransmitter (Acetyl choline) which generates an action potential in the sarcolemma.

Atherosclerosis is caused by deposition of

An animal having pentadactyl limbs without claws belongs to the class

Clotting disorders is occurred because

The impulse for voluntary muscles for forced breathing starts in

Temperature regulation is founds in

While solving the problem of sex determination in large number of insects, it was observed that