You discover a new multicellular organism. The organism has organelles and cell walls composed mainly of cellulose. This new organism could be
A. a plant.
B. a bacterium.
C. an animal.
D. a fungus.
E. an archaea.
A. a plant.
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Prolactin
a. stimulates the mammary glands to produce milk. b. causes the development of breasts and other secondary sexual characteristics in the male. c. acts in concert with FSH to produce milk. d. has secondary effects on reducing the size of the uterus after birth. e. is secreted only after the flow of milk has begun after delivery of the child.
How would you characterize the relationship of species that have many genetic similarities compared to those that do not?
What will be an ideal response?
Some cancers are caused by the overexpression of receptor tyrosine kinases (RTKs). It is known that RTK-signaling pathways commonly stimulate cell division. Why would the overexpression of receptor tyrosine kinases lead to cancer development?
A. If there are too many RTKs on the cell surface, this will promote the inhibition of autophosphorylation. In the absence of autophosphorylation, it is more likely that the RTK downstream signaling pathway will be active. B. RTKs are activated by dimerization, caused by ligand binding. If there are too many receptors on the cell surface, it is possible that these receptors dimerize in the absence of ligand binding, thus stimulating cell division at inappropriate times. C. If there are too many RTKs on the cell surface, this will tend to allow cells to adhere to each other. Once they adhere, RTKs from one cell can bind to RTKs from another cell, and they can activate each other leading to activation of downstream signaling pathways in both cells. D. If there are too many RTKs on the cell surface, it is less likely that inhibitors will bind to all of the available RTKs and block their ability to enter the nucleus. As a result, some of the RTKs will be able to enter the nucleus to stimulate transcription.
An oceanographer might study which of the following?
A) Heat tolerance of coastal barnacles B) The influence of the Loop Current on seasonal growth of open-sea algae C)Yearly oxygen production by salt marsh grasses D)How mole crabs burrow in sand.