Biology Test - 60

Although the Amoeba has no sense organs, It responds to chemical stimuli. It make this determination by chemotaxis, a kind of chemical sense. This is the same response mechanism that our white blood use when they encounter and phagocytize a pathogen.

The statements is generally true about RNA polymerase II is it generally synthesizes various types of mRNAs and small non-coding RNAs.

Bt toxin is produced by a bacterium called Bacillus thuringiensis. This bacterium is known for its insecticidal properties and is widely used in agriculture to control pests. Bt toxin, derived from Bacillus thuringiensis, is effective against a variety of insect pests and is commonly incorporated into genetically modified crops to confer resistance to insect damage. 

Cytokines are a broad and loose category of small proteins that are important in cell signaling. Their release has an effect on the behavior of cells around them. It can be due to immune response or inflammation. Interferons are a type of cytokine. They are released by host cells in response to the presence of pathogens such as viruses, bacteria, parasites, or tumor cells. They allow for communication between cells to trigger the protective defenses of the immune system that eradicate pathogens or tumors.
(B) Cellular barriers - (III) Neutrophils and Macrophages

Cellular barriers are formed by immune cells that prevent the spread and movement of foreign substances in the body. Neutrophils and macrophages are types of white blood cells and are part of the immune system. Neutrophils are the most abundant type of granulocytes and the most abundant type of white blood cells in most mammals. They form an essential part of the innate immune system. Their functions vary from the destruction of bacteria and fungi to the stimulation of other immune cells. Macrophages, on the other hand, are a type of white blood cell that engulfs and digests cellular debris, foreign substances, microbes, cancer cells, and anything else that does not have the type of proteins specific to healthy body cells on its surface in a process called phagocytosis.
(C) Physiological barriers - (IV) Tears and Saliva

Physiological barriers are those which use the body’s own natural processes to prevent infection. For instance, both tears and saliva contain enzymes such as lysozyme which help to break down the cell walls of many kinds of bacteria.
(D) Physical barriers - (I) Mucus coating of the respiratory tract

Physical barriers are the body's first line of defense against pathogens. These barriers are structural in nature. The mucus coating of the respiratory tract is a great example. It traps pathogens, dust, and other particles that enter the nasal passage with each breath, and because the mucus is constantly moved by cilia, it is eventually coughed or sneezed out, or swallowed and destroyed by stomach acids. Thus, it acts as a physical barrier, preventing pathogens from reaching the lungs.

Lemon is a hesperidium type of fruit. It is many chambered fleshy fruit developing from a multicarpellary, syncarpous, multilocular, superior ovary bearing seeds on axile placentation. The leathery epicarp of hesperidium has many glands of aromatic oil. The mesocarp, represented by white fibres, is fused to the epicarp. The epicarp and mesocarp together form the rind. The endocarp is thin and papery. It projects inwards and forms many compartments. The inner wall of endocarp gives out many juicy succulent hairs which form the edible part of the fruit. Hesperidium is a characteristic fruit of the rutaceae; e.g., Citrus aurantifolia (lemon), Citrus reticulata (orange). etc.

The immunity which is induced by vaccines is called as artificial active immunity. In the vaccination or immunization process, small amount of antigen (dead or weakened pathogen) is introduced into the body in the form of vaccine. This induces immune response and antibody formation against the antigen. As a result, body has sufficient antibodies to control the disease. For example: BCG vaccine for tuberculosis, oral polio vaccine 'sabin' etc.

Contralateral loss of pain and temperature is due to injury to the lateral spinothalamic tract.

• Damage to lateral spinothalamic tract leads to loss of pain and temperature on the opposite side of the body below the level of lesion, since the neurons of this tract crosses to the opposite side in the spinal cord.
• Anterior spinothalamic tract carries crude touch and pressure sensations. Fasciculus gracilis and fasciculus cuneatus carries conscious proprioception, fine touch, stereognosis and vibration sensations.

Golden rice is a variety of rice (Oryza sativa) produced through genetic engineering to biosynthesize beta-carotene, a precursor of vitamin A, in the edible parts of rice.

Following are the important points related to Golden rice:

• Golden rice is different from its parental strain due to the addition of three beta-carotene biosynthesis genes to the Golden rice.
• These included two genes from the daffodil plant and a third from a bacterium.
• Researchers used a plant microbe to ferry in the genes into the plant cells.

Regulation of cells activity takes place through flow of energy.

Cells in your body get energy from the foods that are eaten, such as glucose (a sugar). Cellular respiration converts glucose and oxygen into water, carbon dioxide and usable form of energy called ATP.

Theepidermisis the protective outer layer of clonally related cells covering all plant organs. It is made up ofcellulose, hemicelluloses, and pectin.

Functions of the cell wall in the plant:

• Regulatesandcontrols the direction of cell growth.
• Providingstrength, structural support, and maintaining the shape of the cell.
• It supports theentry of smaller molecules moving freely.

Cell Membraneis present inall organisms including plants.

• It is also known as theplasma membrane.
• It is asemi-permeable membrane composed of lipids and proteins.