Problem 35 - Objective Biology for NEET

Question

Find the correct descending order to the percentage proportion of leucocytes in human blood. (a) Neutrophils \(\rightarrow\) Basophils \(\rightarrow\) Lymphocytes \(\rightarrow\) Acidophils (Eosinophils) \(\rightarrow\) Monocytes (b) Neutrophils \(\rightarrow\) Monocytes \(\rightarrow\) Lymphocytes \(\rightarrow\) Acidophils \(\rightarrow\) Basophils (c) Neutrophils \(\rightarrow\) Lymphocytes \(\rightarrow\) Monocytes \(\rightarrow\) Acidophils \(\rightarrow\) Basophils (d) Neutrophils \(\rightarrow\) Acidophils \(\rightarrow\) Basophils \(\rightarrow\) Lymphocytes \(\rightarrow\) Monocytes

Step-by-Step Solution

Answer

The correct answer is (c). The leucocytes in human blood, in descending order of their proportions, are Neutrophils, Lymphocytes, Monocytes, Eosinophils (Acidophils) and Basophils.

Step 1: Analyze the Proportions

Consult a reliable source and note the percentage of each type of leucocytes in human blood. The percentages can vary slightly, but the average proportions are generally as follows: Neutrophils (50%-70%), Lymphocytes (20%-40%), Monocytes (2%-8%), Eosinophils (1%-3%), and Basophils (0.5%-1%).

Step 2: Compare the options

Compare the given answer choices (a), (b), (c), and (d) with the correct proportions of leucocytes discovered in Step 1.

Step 3: Determine the Correct Answer

Find the option that correctly orders the leucocytes from highest to lowest proportion. Given the proportions from Step 1, only option (c) is correct: Neutrophils, Lymphocytes, Monocytes, Eosinophils (Acidophils), and Basophils.

Key Concepts

Neutrophils

Neutrophils play a crucial role in the human immune system. They are specialized types of white blood cells, also known as leukocytes. You'll find that they generally account for about 50%-70% of all leukocytes, making them the most abundant type. This high percentage means they are a significant first line of defense in our body's way of fighting infections.

When a site of infection is detected, neutrophils quickly move to that area to neutralize the threat. They achieve this by consuming invaders like bacteria or fungi. Their action is somewhat like a Pac-Man, gobbling up harmful elements and protecting our body. This makes their speedy response a vital function for general health.

• Neutrophils work primarily in the bloodstream.
• They respond rapidly to infections.
• They form "pus" when they have reached the end of their life cycle.

Lymphocytes

Lymphocytes are another type of leukocyte, and they account for about 20%-40% of the total white blood cell population in human blood. These cells are a vital component of the immune system, tasked with identifying and eliminating foreign invaders.

There are mainly two kinds of lymphocytes: B cells and T cells. B cells produce antibodies, proteins that specifically target and neutralize pathogens. T cells, on the other hand, have a direct attack role, destroying infected cells in the body.

It is the coordinated effort between these two types that allows our bodies to efficiently handle infections and diseases. Without lymphocytes, our body's ability to cope with illnesses would be significantly hampered.

• B cells and T cells are crucial for immune response.
• B cells help produce antibodies.
• T cells target infected cells directly.

Eosinophils

Eosinophils are among the lesser-known leukocytes, contributing only 1%-3% to the total count. Despite their smaller numbers, they perform essential duties within the immune system. They specialize in combating multicellular parasites and certain infections in vertebrates.

Unlike neutrophils, eosinophils are more involved in controlling allergic reactions and modulating inflammatory processes. They do this by releasing enzymes that can neutralize toxins. Their role extends to being involved in asthma reactions, where they help in modulating the inflammation caused.

• Eosinophils manage parasitic infections.
• They control allergic responses.
• They are key in managing asthma-related inflammation.