Tag: biology

Questions Related to biology

If some skeletal muscle fibres are soaked in glycerol or a dilute salt solution, a number of proteins leak out of the fibres without any change in the appearance of the sarcomeres. Such a preparation will contract, if the fibres are supplied with magnesium ions, ATP and calcium ions. The proteins that have leaked out are of the type known as_____________.

muscle contraction locomotion and movements biology

  1. Myosin and enzymes of glycolysis

  2. Myoglobin (oxygen-binding protein)

  3. Enzymes including those of glycolysis and myoglobin

  4. Actin

Show answer
Correct Option: C

Read the statements about the mechanism of muscle contraction and select the correct answer.
I. Acetylcholine is released when the neural signal reaches the motor end plate.
II. Muscle contraction is initiated by a signal sent by CNS via a sensory neuron.
III. During muscle contraction, isotropic band gets elongated.
IV. Repeated activation of the muscles can lead to lactic acid accumulation.

muscle contraction locomotion and movements biology

  1. I and IV alone are correct.

  2. I and III alone are correct.

  3. II and III alone are correct.

  4. I, II and III alone are correct.

  5. I and II alone are correct.

Show answer
Correct Option: A
Explanation:
  • Acetylcholine (ACh) is a neurotransmitter released by motor neurons that binds to receptors in the motor endplate when the neural signal reaches the motor endplate. Neurotransmitter release occurs when an action potential travels down the motor neuron's axon, resulting in altered permeability of the synaptic terminal membrane and an influx of calcium. Hence statement I is correct.
  • Repeated activation of the muscles can cause the anaerobic breakdown of glucose which leads to the formation of lactic acid and its accumulation. Accumulation of lactic acid can irritate muscles and cause discomfort and soreness. Hence Statement IV is correct.
  • So, the correct answer is 'I and IV alone are correct'.

Which of the following option shows correct order of some stages of muscle contraction from the beginning to the end of the process?

muscle contraction locomotion and movements biology

  1. Stimuli $\rightarrow$ Neurotransmitter secretion $\rightarrow$ Release of Ca$^{2+}$ $\rightarrow$ Cross bridges formation $\rightarrow$ Excitation of T-system $\rightarrow$ Sliding of actin filaments

  2. Stimuli $\rightarrow$ Neurotransmitter secretion $\rightarrow$ Excitation of T-system $\rightarrow$ Release of Ca$^{2+}$ $\rightarrow$ Cross bridges formation $\rightarrow$ Sliding of actin filaments $\rightarrow$ H band diminishes

  3. Stimuli $\rightarrow$ Excitation of T-system$\rightarrow $ Neurotransmitter secretion $\rightarrow$ Cross bridges formation $\rightarrow$ Sliding of actin filaments $\rightarrow$ H band diminishes

  4. Stimuli $\rightarrow$ Neurotransmitter secretion $\rightarrow$ Cross bridges formation $\rightarrow$ Excitation of T-system$\rightarrow$  Sliding of actin filaments

Show answer
Correct Option: B
Explanation:

The contraction of skeletal muscle includes ultrastructural and biochemical events. Ultrastructural events lead with stimuli excitation of T-system followed by cross-bridge formation (myosin and actin filaments involved) and the cross-bridge breakage. The biochemical events explain that stimuli lead to neurotransmitter secretion, excitation of T-system and release of Ca$^{2+}$.

Which of the following is not involved in muscle contraction?

muscle contraction locomotion and movements biology

  1. Creatine phosphokinase

  2. Troponin

  3. Calcium ions

  4. All of these are involved in muscle contraction

Show answer
Correct Option: D
Explanation:

  • Myofibril activity is required for muscle contraction on the molecular level. 
  • When ATP binds to myosin, it separates from the actin of the myofibril, which causes a contraction.
  • Creatine phosphokinase helps in the regeneration of ATP.
  • H zone disappears and Z zone moves towards each other.
  • The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin.
  • ATP then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.
So, the correct option is 'All of these' are involved in muscle contraction'.

Muscle contraction is initiated by a signal by the central nervous system via

muscle contraction locomotion and movements biology

  1. Motor nerve

  2. Sensory nerve

  3. Mixed nerve

  4. All of the above

Show answer
Correct Option: A
Explanation:

Most of the muscle actions of the body are voluntary except for the pumping of heart and the reflex action. These muscle receive a signal through the motor nerves , send by the brain or the CNS.

So the correct option is ' Motor nerve '.

Consider the following statements each with one or two blanks.
(i) Repeated activation of the muscles can lead to the accumulation of  (A)  due to anaerobic breakdown of glycogen in them, causing fatigue.
(ii) The globular head of meromyosin is an active ATPase enzyme and has binding sites for (B) and active sites for (C).
(iii) This central part of thick filament, not overlapped by thin filaments is called the  (D) .
Which one of the following options correctly fills the concerned blanks?

muscle contraction locomotion and movements biology

  1. (A) - glucose, (D) - A-band

  2. (A) - pyruvic acid, (B) - troponin, (C) - myosin

  3. (B) - ATP, (C) - actin, (D) - H-zone

  4. (A) - lactic acid, (D) - I-band

Show answer
Correct Option: C

Relaxation of muscle is due to -

muscle contraction locomotion and movements biology

  1. Pumping of $Ca^{+2}$ into sarcoplasmic cisternae

  2. Presence of ATP

  3. Confirmational change in troponin and masking of actin filaments

  4. a and c

Show answer
Correct Option: A
Explanation:

When calcium is pumped back into the sarcoplasmic reticulum breaking the link between actin and myosin. Actin and myosin return to their unbound state causing the muscle to relax.

So, the correct option is 'Pumping of 
Ca+2Ca+2 into sarcoplasmic cisternae'.

ATPase of the muscle is located in:

muscle contraction locomotion and movements biology

  1. actinin

  2. troponin

  3. myosin

  4. actin

Show answer
Correct Option: C
Explanation:

The myosin filament has meromyicin and it has two important parts, a globular head and a tail. The globular head has the site for ATPase enzyme and has binding sites for ATP and active sites for actin.

This helps in the attachment of actin filament during the sliding motion.
So, the correct option is 'myosin'

Vernalization can remove Kernel wrinkles in:

vernalisation plant growth growth and development plant growth and development biology

  1. Wheat

  2. Petkus rye

  3. Maize

  4. Rice

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Correct Option: A
Explanation:
  • Vernalisation is defined as the qualitative or quantitative dependence of plants on exposure to a low temperature to flower. Temperature affects flowering, metabolic activities, and germination of seeds in plants. Plants that grow in mild weather germinate at low temperatures whereas those that grow in hot regions germinate at high temperatures. 
  • Some plants need exposure to a low temperature to germinate. Furthermore, a plant can be induced to flower in a growing season by exposing it to low temperature. Therefore, it shortens the vegetative phase and hastens flowering in plants. 

So, the correct answer is A.

Vernalization is subjected to plants growing in 

vernalisation plant growth growth and development plant growth and development biology

  1. Tropical areas

  2. Sub tropical

  3. Temperate areas

  4. Hot areas/Arctic region

Show answer
Correct Option: C
Explanation:
Vernalization refers to the phenomenon of inducing flowering in plants by subjecting them to prolonged cold temperatures. After vernalization, plants acquire the ability to flower. Vernalization is subjected to plants growing in Temperate(temperature in these regions is moderate) areas.
So, the correct answer is 'Temperate areas'.