The main phenomenon that increases the efficiency of gas exchange in fish gills is the
A. countercurrent exchange mechanism.
B. co-current exchange mechanism.
C. high degree of oxygen saturation of water.
D. back-and-forth movement of water that maximizes oxygen uptake.
E. very high blood pressure found in the circulatory system of fishes.
A. countercurrent exchange mechanism.
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Conservationists have identified 25 areas worldwide as hotspots. This means these areas
A. are currently being preserved. B. have serious pollution problems and are being targeted for cleanup. C. have high numbers of endemic species, and those numbers are increasing. D. have high numbers of endemic species, and those numbers are decreasing. E. have the highest numbers of invasive species worldwide.
What is the function of the contractile vacuole?
A. to help single-celled organisms maintain homeostasis in a hypotonic environment B. to help single-celled organisms change shape in response to environmental changes C. to help maintain water balance for singlecelled organisms living in a hypertonic environment D. to maintain cell shape through turgor pressure
How many chromosomes are found in a single human cell at the end of each of the following meiotic stages? ________ prophase I ________ anaphase I ________ prophase II ________ telophase II
What will be an ideal response?
You lose track of your friend in a store and start looking for her. Which strategy represents the use of a search image?
A) You ask a woman if she has seen anyone around this part of the store. B) You think about what color clothing your friend is wearing and look for that color. C) You go to the department in the store where your friend most likes to shop. D) You return to the last place you saw your friend.