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Jul 7, 2024 · protein, highly complex substance that is present in all living organisms. Proteins are of great nutritional value and are directly involved in the chemical processes essential for life. The importance of proteins was recognized by chemists in the early 19th century, including Swedish chemist Jöns Jacob Berzelius, who in 1838 coined the term ...
Jul 7, 2024 · T cell, type of leukocyte (white blood cell) that is an essential part of the immune system. T cells are one of two primary types of lymphocytes — B cells being the second type—that determine the specificity of immune response to antigens (foreign substances) in the body. T cells originate in the bone marrow and mature in the thymus.
Jul 5, 2024 · heart, organ that serves as a pump to circulate the blood. It may be a straight tube, as in spiders and annelid worms, or a somewhat more elaborate structure with one or more receiving chambers (atria) and a main pumping chamber (ventricle), as in mollusks. In fishes the heart is a folded tube, with three or four enlarged areas that correspond ...
Jun 30, 2024 · antibody, a protective protein produced by the immune system in response to the presence of a foreign substance, called an antigen. Antibodies recognize and latch onto antigens in order to remove them from the body. A wide range of substances are regarded by the body as antigens, including disease-causing organisms and toxic materials such as ...
Jun 19, 2024 · Define Organ.. Ans: Hint: In biology, the basic and fundamental unit of life is a cell, whereas those cells divide to form the tissues, there are so many types of tissues present in the body, and these tissues of similar function are together to prod...
Jul 1, 2024 · gamete, sex, or reproductive, cell containing only one set of dissimilar chromosomes, or half the genetic material necessary to form a complete organism (i.e., haploid). Gametes are formed through meiosis (reduction division), in which a germ cell undergoes two fissions, resulting in the production of four gametes.
1 day ago · brain, the mass of nerve tissue in the anterior end of an organism. The brain integrates sensory information and directs motor responses; in higher vertebrates it is also the centre of learning. The human brain weighs approximately 1.4 kg (3 pounds) and is made up of billions of cells called neurons. Junctions between neurons, known as synapses ...
