Biology 151 Exam A+ Pass

Biology 151 Exam A+ Pass Imagine there are 25 different species of protists living in a tide pool. Some of these species reproduce both sexually and asexually, and some of them can reproduce only asexually. The pool gradually becomes infested with disease-causing viruses and bacteria. Which species are more likely to thrive in the changing environment? - Answer - The sexually reproducing species is more likely to thrive. Where does most of the mass of a tree come from? - Answer - carbon dioxide What are the products of light reactions that are subsequently used by the Calvin cycle? - Answer - ATP and NADH Where does the Calvin cycle take place? - Answer - in the Stroma of chloroplast in photosynthetic organisms Absorption spectrum of chlorophyll a and the action spectrum for photosynthesis (the range of light wavelengths that can power photosynthesis) are not the same. Why are they different? - Answer - Other pigments absorb light in addition to chlorophyll a. In plant photosynthesis, the electron donor for the light dependent reaction is....? - Answer - Water The overall chemical reaction that occurs in photosynthesis is.....? - Answer - 6 CO2 + 6 H2O = 6 O2 + C6H12O6 Which of the following types of organisms carry out photosynthesis? - Answer - Plants, Algae and Bacteria. Studies have shown that eating a variety of different - colored plant foods is beneficial for humans. This is because....? - Answer - Photosynthetic pigments can act as antioxidants The electron that is donated to photosystem 1 comes from....? - Answer - Photosystem 2 What type of signaling occurs when a death promoting signal is secreted from a nearby cell, travels through the extracellular fluid, and binds to a receptor on the target cell, ultimately triggering apoptosis? - Answer - Paracrine signaling (moves through extracellular fluid) The steroid testosterone is most likely to exert its effects by regulating....? - Answer - Expression of genes When a ligand binds to this type of receptor, it associates with a membrane bound protein that is activated by swapping out GDP for GTP. - Answer - A G protein coupled receptor In C. Elegan worms, the normal function of Ced9 is to....? - Answer - Suppress apoptosis in the absence of death - signaling molecules. When epinephrine interacts with one cell, it causes that cell to increase production of a certain protein, but when it interacts with a different cell, it triggers that cell to divide. Which of the following is a possible mechanism by which the two cells might respond differently to the same epinephrine signal? - Answer - The cells might have different types, numbers and signal different signal transduction pathways. Ligand X works by increasing production of protein A in a cell. Up to a point, increasing the rate of production of protein A, but once all the cell's receptors for ligand x are occupied, there is no further change in the rate of production of protein A. This phenomenon is known as.....? - Answer - Saturation The enzyme that catalyzes the chemical reaction that creates cAMP is.....? - Answer - Adenylyl cyclase receptor tyrosine kinases are receptors that....? - Answer - Catalyze the addition of a phosphate removed from ATP to a tyrosine amino acid. All of the following are ways that a cell might respond to an extracellular signal; which of the options below would you expect to happen the slowest? - Answer - Protein production. Decreased apoptosis might lead to - Answer - accumulation of old cells, Cancer and Improper embryonic development Which of the following is a reason why an organism might need to be able to make new cells? - Answer - Reproduction, growth, wound healing, and replaced old or damaged cells. Which of the following sequence of cell-cycle phases is characteristics of eukaryotes? - Answer - G1 ( gap 1) - S (DNA Synthesis) - G2 (Gap 2) - M (Mitosis)- C (cytokinesis) In the S phase of the cell cycle....? - Answer - DNA is replicated