Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

People recovering from long illness are often advised to include the alga Spirulina in their diet because it

  • makes the food easy to digest

  • is rich in proteins

  • has antibiotic properties

  • restores the intestinal microtlora


B.

is rich in proteins

Spirulina is a blue-green algae. Spirulina platensis is one of the richest source of protein, containing 40-50 percent crude protein on dry weight basis which under favourable condition may reach upto 70 percent. Its protein has balanced composition containing all essential amino-acids and lysine and tryptophan being present in sufficient quantities.

It is also rich in vitamins, particularly Vit. B12 which is not common in plant products and contains considerable amounts of fats, carbohydrates and minerals. It's lipids are made up of unsaturated fatty acids that do not form cholesterol.


2.

Which one of the following is a matching pair?

  • Lubb - sharp closure of AV valves at the beginning of ventricular systole

  • Dup - sudden opening of semilunar valves at the beginning of ventricular diastole

  • Pulsation of the radial artery - valves in the blood vessels

  • Initiation of the heart beat - Purkinje fibres


A.

Lubb - sharp closure of AV valves at the beginning of ventricular systole

The gradually increasing contraction of ventricular muscles during systole first causes the closure of bicupsid and tricupsid valves (AV valves), producing a low- pitched "lubb" sound. Later, it causes the opening of the semilunar valves of systemic and pulmonary aorta. At the end of ventricular systole, semilunar valves shut, producing the second, louder heart sound, the "dup". Thus, each heart beat is accompained by a "lubb- dup" sound.


3.

The source of somatostatin is same as that of

  • thyroxine and calcitonin

  • insulin and glucagon

  • somatotropin and prolactin

  • vasopresin and oxytocin


D.

vasopresin and oxytocin

The source of somatostatin is same as that of vasopressin and oxytocin. Somatostatin is produced from hypothalamus (somatostatin neuron) and oxytocin and vasopressin are also produced in the nuclei of hypothalamus, though later they are stored and released from posterior pituitary.


4.

An example of competitive inhibition of an enzyme is the inhibition of:

  • succinic dehydrogenase by malonic acid

  • cytochrome oxidase by cyanide

  • hexokinase by glucose-6-phosphate

  • carbonic anhydrase by carbon dioxide


A.

succinic dehydrogenase by malonic acid

In competitive inhibition, an inhibitor that resembles the normal substrate binds to the enzyme, usually at the active site and prevents the substrate from binding. 

An example of competitive inhibition of an enzyme is the inhibition of succinic dehydrogenase by malonic acid. It is the simple type of competitive inhibition. A competitive inhibitor resembles the substrate and binds to the active site of the enzyme. The substrate is then prevented from binding to the same active site.


5.

A person passes much urine and drinks much water but his blood glucose level is normal. This condition may be the result of:

  • a reduction in insulin secretion from pancreas

  • a reduction in vasopressin secretion from posterior pituitary

  • a fall in the glucose concentration in urine

  • an increase in secretion of glucagon


B.

a reduction in vasopressin secretion from posterior pituitary

Vasopressin or ADH secreted from posterior pituitary stimulates reabsorption of water by the distal convoluted tubule and the collecting renal tubules and thus regulates urine volume. It has no such important effect on glucose metabolism. Therefore, a person whose blood glucose level is normal, but passes much urine and drinks much water has a reduction in vasopressin secretion which ultimately leads to diabetes insipidus.


6.

Which one of the following is a sesamoid bone?

  • Pelvis

  • Patella

  • Pterygoid

  • Pectoral girdle


B.

Patella

Patella is a sesamoid bone. Sesamoid bones are formed by ossification of a tendon where the tendon moves over a bony surface.


7.

Which one of the following is a matching pair of a certain body feature and its value/count in a normal human adult?

  • Urea- 5 - 10 mg/100 ml of blood

  • Blood sugar (fasting) - 80 - 100 mg/100 ml

  • Total blood volume - 3 - 4 litres

  • ESR in Wintrobe method - 9 -15 mm in males and 20 - 34 mm in females


B.

Blood sugar (fasting) - 80 - 100 mg/100 ml

Normal blood sugar level in adult human varies from 80 - 100 mg/100 ml (fasting) to 100-120 mg/100 ml (after meal).

Normal blood urea is 20 - 40 mg/dl

Total blood volume is 4 - 5 litres

ESR or Erythrocyte Sedimentation Rate in wintrobe method is 0 - 9 mm in male and 0 - 20 mm in female.


8.

Photorespiration in C3 plants starts from:

  • phosphoglycerate

  • phosphoglycolate

  • glycerate

  • glycine


B.

phosphoglycolate

In the process of photorespiration oxygen combines with RuBP (Ribulose- biphosphate) in chloroplast as following

O2 + RuBP Rubisco3- Phosphoglycerate + 

                              2- Phosphoglycerate CO2

Phosphoglycolate enters in peroxisomes and is finally converted to CO2.


9.

Excessive stimulation of vagus nerve in humans may lead to:

  • hoarse voice

  • peptic ulcers

  • efficient digestion of proteins

  • irregular contractions of diaphragm


B.

peptic ulcers

Vagus nerve is known as pneumogastric nerve. It helps control several muscles of the throat and of the voicebox. It helps in regulating the heart rate and keeping the gastrointestinal tract in working order. It also carry sensory information from the internal organs back to the brain.

Excessive stimulation of vagus nerve in humans may lead to peptic ulcer. Vagal stimulation increases peristalsis which in excess, secretes more HCl and pepsin from stomach. These causes erosion through protective barrier of mucus and muscularis mucosa into the submucosa which leads to peptic ulcer.


10.

A person is wearing spectacles with concave lenses for correcting vision. While not using the glasses, the image of a distant object in his case will be formed

  • on the blind spot

  • behind the retina

  • in front of the retina

  • on the yellow spot


C.

in front of the retina

As the person uses spectacles having concave lens, he must be suffering from myopia or short-sightedness. Here the eyeballs become elongated, so that parallel rays are focussed in front of retina.

Myopia is an eye disorder where light focuses in front of retina. This causes distant objects appear normal. It is also known as short- sightedness.