Which of the following molecules was NOT present in the pre-biotic environment?
a) methane (CH4)
b) triethylene glycol
c) ammonia (NH3)
d) water (H20)
e) hydrogen sulfide (H2S)
Answer: b) triethylene glycol
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Receptor mediated endocytosis
A. involves formation of caveolae that are enriched in cholesterol and caveolin. B. depends on formation of clathrin coated pits that pinch off. C. depends on formation of clathrin coated pits that pinch off and is used to internalize molecules such as hormones, growth factors, iron, and cholesterol. D. is used to internalize molecules such as hormones, growth factors, iron, and cholesterol. E. is typically used to internalize plasma membranes added by exocytosis.
Gene silencing in eukaryotes is often achieved through chromatin structure
Indicate whether the statement is true or false
Which of the following includes some of the benefits of photosynthesis?
A. It is a source of carbon dioxide. B. It is an oxygen source as well as a source of stored energy. C. It stores chemical energy. D. It enhances the greenhouse effect.
Answer the following questions true (T) or false (F)
1. Companion cells play a role in keeping xylem cells alive. 2. The male gametophyte generation develops largely within pollen grains of angiosperms. 3. The anther in a flower produces microspores.