Practice free Zoology NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
What is true about RBCs in humans?
Nearly 20-25 per cent of CO2 is transported by RBCs. It is caused by haemoglobin as carbamino haemoglobin. 70 per cent of CO2 is carried as bicarbonates.
About 97 per cent of O2 is transported by RBCs in the blood. The remaining 3 per cent of O2 is carried in dissolved state through the plasma.
Which two of the following changes (1-4) usually tend to occur in the plain dwellers when they move to high altitudes (3,500 m or more)?
1. Increase in red blood cell size
2. Increase in red blood cell production
3.Increased breathing rate
4 increase in thrombocyte count Changes occurring are
When a person moves to higher altitudes, the PO2 and total atmospheric pressure decrease. Hypoxia stimulates the JG-cells of the kidney to release erythropoietin hormone, which stimulates erythropoesis in bone marrow causing polycythemia. Hypoxia will also increase breathing rate. Initially the size of RBCs will also increase but with increase in number of RBCs, the size of RBCs becomes normal.
People living at sea level have- around 5 million RBC per cubic millimeter of their blood whereas those living at an altitude of 5400 metres have around 8 million. This is because at high altitude:
At high altitudes, the atmospheric O2 level is less and hence, more RBCs are needed to absorb the required amount of O2 to survive. That is why, the people living at sea level have around 5 million RBC/mm3 of their blood whereas those living at an altitude of 5400 meters have around 8 million RBC/mm3 of their blood.
Which one of the following statements is incorrect ?
Residual capacity is that portion of air contained in the lungs which can not be expelled even by the most violent expiratory effort. Residual air is actually part of dead space, it doesn't play active part in respiration. Therefore, residual air in lungs doesn't affect efficiency of respiration.
In the tissues, high concentrations of carbon doxide
(c) As the CO2 content of blood increases the pH of the blood falls. This produces the decrease in oxygen affinity of haemoglobin. This is called as Bohr effect and is closely related to the fact that deoxygenated haemoglobin (deoxy haemoglobin) binds hydrogen ion more actively than does the haemoglobin. This facilitates gaseous exchange, because more oxygen is released in the tissues where the amount of carbon dioxide is rising due to metabolic activity. At the same time, more oxygen is taken up at the lungs or gills where the amount of carbon dioxide is low.
The respiratory centre in the brain is stimulated by
(c) Respiratory centre controls the rate of respiration. Respiratory centre is located in medulla oblongata and pons. It has the following components
(i) inspiratory area connected to inspiratory muscles,
(ii) Pneumotaxic area
(iii) Expiratory area
(iv) chemosensitive area.
Chemoreceptors located on carotid and aortic bodies are sensitive to carbon dioxide levels in arterial blood. They send information to respiratory centre. Oxygen does not have a significant direct effect on the respiratory centre of the brain.
Which of the following match is correct?
(a) Emphysema means abnormal accumulation of air in the tissues (lungs). In pulmonary emphysema the air sacs (alveoli) of the lungs are enlarged and damaged, which reduces the surface area for the exchange of oxygen and carbon dioxide. Severe emphysema causes breath-lessness, which is made worse by infections. Pneumonia is inflammation of the lung caused by bacteria, in which the air sacs (alveoli) become filled with inflammatory cells and the lung becomes solid. The symptoms include those of any infection (fever, malaise, headaches, etc.), together with cough and chest pain. Silicosis, a lung disease, is a form of pneumoconiosis produced by inhaling silica dust particles. It affects workers in hard-rock mining and tunnelling, quarrying, stone dressing, sand blasting, and boiler scaling. Silica stimulates fibrosis of lung tissue, which produces progressive breathlessness and considercbly increased susceptibility to tuberculosis. Asthma is the condition of subjects with widespread narrowing of the bronchial airways, which changes in severity over short periods of time (either spontaneously or under treatment) and leads to cough. wheezing, and difficulty in breathing.
When a man inhales air containing normal concentration of O2 as well as CO he suffers from suffocation because
(b) Affinity of carbon monoxide for haemoglobin is 200 times more than oxygen. At 0.5 partial pressure, CO combines witli 50% of haemoglobin. It produces a relatively stable compound called carboxy - haemoglobin. This causes low supply of oxygen to the body which is characterised by headache, dizziness, nausea, etc.
Diffusion membrane consists of
Refer NCERT, Heading 17.3, page-273.
What percentage of Carbon dioxide is transported by RBCs
Refer NCERT, Heading 17.4, para 1, page-274
Ready to ace NEET?
Free access · No credit card required
Yes. You can attempt every Zoology question on this page for free without logging in, and check the correct answer with a detailed explanation instantly.
No account is required to attempt questions and view answers. A free account adds bookmarks, personal notes, and progress tracking.
The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.