52 practice MCQs on the human heart, blood vessels and blood, the respiratory system and gas exchange, lymph, and water and food transport in plants. Every question has the correct answer and an explanation.
Start free — 20 questionsTransport, Circulation and Gaseous Exchange is part of the MDCAT Biology syllabus. This page collects Transport, Circulation and Gaseous Exchange MCQs in the style of past MDCAT papers — below are 12 of them with answers and explanations, and the full set of 52 questions is in the HighYield MDCAT QBank.
This chapter covers: the human heart, blood vessels and blood, the respiratory system and gas exchange, lymph, and water and food transport in plants.
Correct answer: A. Hepatitis
Hepatitis (B and C) is transmitted via blood and blood products, unlike cholera, influenza and candidiasis which spread by other routes.
Correct answer: D. Lacteal
The lymph vessel located within each intestinal villus, responsible for absorbing dietary fats, is called the lacteal.
Correct answer: A. Nucleus
Mature mammalian red blood cells lack a nucleus, having expelled it during development to maximize space for haemoglobin.
Correct answer: D. Lymphocytes
Neutrophils are the most abundant type of white blood cell, forming the first line of defence against bacterial infection.
Correct answer: D. As bicarbonate
About 70-85% of CO2 in the blood is transported as bicarbonate ions, formed after CO2 combines with water in red blood cells.
Correct answer: D. Two phases
Breathing consists of two phases: inspiration (inhalation) and expiration (exhalation).
Correct answer: A. Cell-mediated response
When T-lymphocytes recognize and attack microorganisms or transplanted tissue directly, this is termed the cell-mediated immune response.
Correct answer: B. Humoral Response
When B-cells (via plasma cells) release antibodies into blood plasma, tissue fluid and lymph, this is called the humoral immune response, as opposed to the cell-mediated response driven by T-cells.
Correct answer: C. 3
The ABO blood group antigens are encoded by one genetic locus, the ABO locus, which has three alternative (allelic) forms—A, B, and O. A child receives one of the three alleles from each parent, giving rise to six possible genotypes and four possible blood types (phenotypes).
Correct answer: B. Multiple Alleles
In the ABO blood group system, there are more than two alleles (A, B, and O) that control the blood type in a population. Each individual inherits two alleles from their parents, resulting in a combination of these multiple alleles determining their blood type.
Correct answer: B. The wall of each alveolus is 0.1 cm thick
Option B regarding alveoli is not correct.The walls of alveoli are extremely thin, only about 0.0002 cm thick. This allows for the rapid diffusion of gases between the alveoli and the blood capillaries that surround them.while all other statements regarding alveoli are correct.
Correct answer: C. Valine
Option C is correct. In sickle cell anemia, glutamic acid in the hemoglobin molecule is replaced by valine. This single amino acid substitution leads to the hemoglobin molecules becoming sticky and clumping together when oxygen levels are low. This causes the formation of sickle-shaped red blood cells, which can obstruct blood vessels and lead to severe complications such as pain, stroke, and other health issues. Sickle cell anemia is a genetic condition resulting from a mutation in the hemoglobin gene and is especially prevalent among individuals of African descent. The other options (Proline, Glutamine, Glycine) do not correctly identify the amino acid involved in this specific mutation, and therefore, do not explain the pathology of sickle cell anemia.
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