Tag: zoology

NAD+ and FAD are co-enzymes required for the completion of many biochemical pathways. However, there is no need for an enormous amount of synthesis of either of these co-enzymes as there as a mechanism of recycling the co-enzymes after completion of one step in the metabolic pathway. These co-enzymes are predominantly required for the synthesis of ATP (energy currency of the cell) and will be used in the electron transport chain for the production of the same. So, they are not required to be synthesized in huge quantities but they play a crucial role in cell energetics.

The skin is the largest organ of the body, with a surface area of 18 square feet. Its two main layers are the epidermis (outer layer) and dermis (inner layer). The epidermis has several strata (layers) that contain four cell types. Keratinocytes produce keratin, a protein that gives skin its strength and flexibility and waterproofs the skin surface.

The very first line of defense against any invasion of the human body is a set of physical barriers between the inside of the body and the outer world. Defense systems like skin, tears, mucous membranes are considered the non-specific barriers and the first line of defense.
So, the correct answer is option A.

Phagocytes are cells that protect the body by ingesting harmful foreign particles, bacteria, and dead cells, thereby involving in the process of phagocytosis. They are essential for fighting infections and for subsequent immunity. The phagocytes include neutrophils and monocytes.
So, the correct answer is option A.

Human body produces antibody to immunize our body from the action of foreign material. Antibody recognizes foreign material binds to it and triggers immune response inside out body leading to phagocytosis.

Hydrochloric acid (HCl) is secreted by the parietal cells of the stomach. It is highly acidic (pH 1.5 to 2) in nature and almost all the pathogens which enter the stomach through the ingested food are killed at this pH. The digestive enzyme pepsin released by the stomach can digest proteins but cannot actually kill the pathogens. Hence, the correct answer is 'HCl'.

The skin and the surface of mucous membranes act as an anatomical barrier and prevent the entry of microorganisms inside the body. The skin maintains the pH about 3 to 5 which retards the growth of microbes and mucous entraps foreign microorganisms and cilia propel microbes out of the body. Thus they prevent the entry of microorganisms. Hence, the correct answer is 'All of the above'.

Parathyroid gland regulates calcium levels in the body. It produces a hormone called parathyroid hormone (PTH). PTH raises the blood calcium level by bone desorption leading to calcium release when the blood calcium level is too low. Another way that parathyroid hormone works is by increasing the body's ability to absorb calcium from food and also increasing the kidney's ability to hold on to calcium that would otherwise be lost in the urine. , PTH is released to bring the calcium level back to normal.  so, the correct answer is option C.

Phagocytosis is the process of ingestion of extracellular particulate material from environment. It is conducted by some specialized cells called the phagocytes. The blood cells, monocytes, neutrophils and macrophages are all phagocytes. Hence, the correct answer is 'All of the above'.