Question
What is a function of some white blood cells?
A to carry glucose
B to carry oxygen
C to produce antibiotics
D to produce antibodies
▶️Answer/Explanation
D to produce antibodies
White blood cells, also known as leukocytes, play a crucial role in the immune system. One of their main functions is to produce antibodies, which are proteins that help identify and neutralize foreign substances (antigens) such as bacteria, viruses, and other pathogens. Antibodies bind to specific antigens and mark them for destruction by other immune cells, thus defending the body against infections and diseases.
Question
The photograph shows two blood cells, X and Y.
▶️Answer/Explanation
Ans: B
The two types of blood cells you mentioned, X and Y, have distinct roles in the human body.
1. Blood cells X (typically referred to as red blood cells or erythrocytes): These cells are responsible for carrying oxygen throughout the body. They contain a protein called hemoglobin, which binds to oxygen in the lungs and transports it to tissues and organs that require oxygen for their metabolic processes. Red blood cells are produced in the bone marrow and have a characteristic biconcave shape, allowing for increased surface area and efficient oxygen exchange.
2. Blood cells Y (referred to as white blood cells or leukocytes): These cells play a crucial role in the immune system’s defense against pathogens, such as bacteria, viruses, and other harmful substances. Among their various functions, white blood cells are involved in producing antibodies. Antibodies, also known as immunoglobulins, are specialized proteins that recognize and bind to specific antigens present on the surface of pathogens. This binding triggers immune responses, such as neutralizing or eliminating the pathogens.
Question
How does blood change as it passes through a kidney?
A It gains glucose.
B It gains salts.
C It loses protein.
D It loses urea.
Answer/Explanation
D
It loses urea.
As blood passes through the kidney, it undergoes a process known as renal filtration, reabsorption, and secretion. These processes are responsible for the formation of urine and involve various changes to the composition of the blood.
One of the primary functions of the kidney is to filter waste products from the blood, including urea, a nitrogenous waste produced by the breakdown of proteins in the body. During renal filtration, small molecules like urea, water, electrolytes, and other waste products are filtered out of the blood through tiny filtering units called nephrons.
After filtration, the resulting fluid, known as the filtrate, then undergoes reabsorption. Important substances such as glucose, salts (including ions like sodium, potassium, and chloride), and water are selectively reabsorbed back into the bloodstream, helping to maintain the body’s balance of these substances. Glucose, for example, is almost completely reabsorbed in a healthy kidney, preventing its loss in the urine.
During this process, certain waste products and excess substances that were initially present in the filtrate, including urea, are actively secreted into the renal tubules by the cells of the nephrons. The tubules play a crucial role in regulating the final composition of the urine by reabsorbing some substances and actively secreting others.
Ultimately, as blood passes through the kidney and undergoes these processes of filtration, reabsorption, and secretion, it loses urea, a waste product, which is excreted in the urine.
Question
The diagram shows human blood cells, as seen under a microscope.
What is the function of cell X?
A to carry glucose
B to carry oxygen
C to defend against disease
D to make the blood clot
▶️Answer/Explanation
B
Based on the diagram showing human blood cells under a microscope, cell X represents red blood cells, also known as erythrocytes. Red blood cells are responsible for carrying oxygen from the lungs to the rest of the body’s tissues and organs. The red blood cells contain a protein called hemoglobin, which binds to oxygen molecules in the lungs, forming a compound called oxyhemoglobin. This binding of oxygen is reversible, meaning that in areas of the body with lower oxygen concentrations (like tissues and organs), oxyhemoglobin releases the oxygen to the cells that need it for various metabolic processes.
As red blood cells travel through the circulatory system, they pick up oxygen in the lungs during inhalation and deliver it to cells throughout the body. Conversely, they collect carbon dioxide, a waste product of cellular metabolism, and transport it back to the lungs, where it is expelled during exhalation.
Question
Which substance is transported by hemoglobin?
A nitrogen
B oxygen
C urea
D water
▶️Answer/Explanation
B
Hemoglobin is a protein found in red blood cells and is responsible for transporting oxygen from the lungs to various tissues and organs throughout the body. It binds to oxygen in the lungs, forming oxyhemoglobin, and releases it in tissues with lower oxygen concentrations, facilitating gas exchange and cellular respiration.