Explain how calcium is needed for muscle contraction.
What will be an ideal response?
Calcium is stored in the sarcoplasmic reticulum of muscle cells. When nervous stimulus triggers a muscle contraction, calcium is released from the sarcoplasmic reticulum, and diffuses rapidly throughout the cytoplasm of the muscle cell. It becomes attached to tropomyosin, causing it to change shape, and move away from the myosin binding site on the actin molecule. Myosin cross-bridges can then attach to the actin at the binding site, and muscle contraction begins.
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Which biochemical pathway fits the data presented?
Assume that a series of compounds has been discovered in Neurospora. Compounds A–F appear to be intermediates in a biochemical pathway. Conversion of one intermediate to the next is controlled by enzymes that are encoded by genes. Several mutations in these genes have been identified and Neurospora strains 1–4 each contain a single mutation. Strains 1-4 are grown on minimal media supplemented with one of the compounds A-F. The ability of each strain to grow when supplemented with different compounds is shown in the table (+ = growth; o = no growth).
media supplement
A) A ? B ? C ? D ? E ? F
B) A ? B ? C ? F ? D ? E
C) F ? B ? C ? D ? A ? E
D) A ? B ? C ? D ? F ? E
E) A ? B ? F ? E ? C ? D
In 2010, India had a population of 1,170,000,000, a birthrate of 0.027, and a death rate of 0.013. Approximately, by how much did the Indian population grow in 2010?
A. 170,000,000 B. 17,000,000 C. 1,700,000 D. 17,000 E. 170,000
Organisms "X" and "Y" are suspected to be the same species. Which of the following will provide the
ultimate proof? a. interbreeding b. anatomy c. physiology d. ecology e. behavior
Cartilage is well supplied with blood vessels
Indicate whether the statement is true or false