ACP Biology Review for Exam! Questions & Accurate answers, rated A+

ACP Biology Review for Exam! Questions & Accurate answers, rated A+ What do organisms use feedback mechanisms for? - Organisms use feedback mechanisms to regulate growth and reproduction, and to maintain dynamic homeostasis. Lactation in mammals - Positive feedback reinforces a stimulus, leading to an even greater response. Suckling by an infant stimulates sensory neurons in the nipples, generating signals in the nervous system that reach the hypothalamus. Nerve impulses from the hypothalamus then trigger the release of the neurohormone oxytocin from the posterior pituitary gland. In response to the oxytocin, the mammary gland secrete milk. Milk release leaders to more suckling and more stimulation. Onset of labor in childbirth - The positive feedback loop reinforces a stimulus causing an even greater response. When mammals give birth, oxytocin induces target cells in the uterine muscles to contract. This causes the hypothalamus to produce even more oxytocin, and more contractions. Ripening of fruit - The positive feedback loop reinforces a stimulus, causing an even greater response. When a fruit ripens, it release ethylene which is taken up by surrounding fruit. This causes the fruits to produce more ethylene, amplifying the process. Diabetes mellitus in response to decreased insulin - Diabetes mellitus is caused by a deficiency of insulin (type I diabetes) or a decreased response to insulin in target tissues (type II diabetes). In type I, the immune system destroys the beta cells in the pancreas. Therefore, there is no insulin to dock with activate the target cells: cannot produce a signaling pathway, so you cannot activate the glucose receptor to take in glucose and convert it into glycogen. In type II, the target cells do not respond to the insulin so you cannot activate the glucose receptor to take in glucose. Describe the two types of specific responses in the Mammalian immune system - The cell-mediated response is part of the third line of defense (specific). Macrophages ingest a foreign antigen. They, they display part of the antigen with MHC proteins on their surface. They release interleukin, which is a cytokine. The interleukin activates T Helper cells to recognize the antigen and trigger the cell mediated response. The T helper cells stimulate other T Helper cells to divide and this creates two types of cells. The T Killer cells which kill infected or cancerous cells. And the T memory cells which are part of the second immune response. They recognize the repeat offender and produce more antibodies for a faster immune response. Humoral Response: The macrophages ingest the foreign antigen. Then, they display part of the antigen with MHC protein on their membrane surface. They also release interleukin, a cytokine. This helps the T Helper Cell to bind and recognize the antigen. This causes a response called the humoral or anti-medicated response. The B cells bind to the loose antigen (bacteria or virus) to recognize it. Then, the T Helper Cells stimulate the B cells to divide and create two kinds to cells. The plasma B cells secrete antibodies which bind to and neutralize the invader. Then the macrophages engulf and destroy the anti-body covered pathogen. The B memory cells are part of the secondary immune system. Explain how antigens and antibodies work together. - Antigens is anything foreign to the immune system. Antibodies are produced by B plasma cells in the humoral response. Each B cell has a specific antigen recognition site on its surface. When it meets that antigen, it becomes activated. Undergoes division: B memory cells and B plasma cells. The B plasma cells secrete antibodies. Each antibody is specific to the foreign antigen. They bind to and neutralize the antigen. Antibodies are protein molecules which means that the sequence of amino acids gives them specificity to antigens. They fit like a key in a lock. Mark for destruction Chromosome* - structural unit made up of DNA and protein Chromatid* - ½ of a duplicated chromosome Gene - heritable factor that controls or influences a specific characteristic, consisting of a length of DNA occupying a particular position on a chromosome (locus) Allele - different form of a specific gene Gene locus - specific position of a gene State the components of a chromosome. - DNA & protein State the number of chromosomes present in a single human diploid cell. - 46 Approximate # of genes in a Human - 22,333 Approximate # of genes in a plant - 30,434 What organism has more genes than humans? - grape w/ 30,434 What organism has less genes than humans? - insect w/ 14889 State the definition of the genome: - entire genetic material of an organism