The cell membrane can be described most accurately as
A) permeable to all small molecules and ions.
B) impermeable to larger molecules independent of their chemical characteristics.
C) permeable to some molecules and impermeable to others.
D) impermeable to all polar molecules.
E) permeable to all molecules except water.
Answer: C
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All of the following statements about cellulose are true EXCEPT:
A. Cellulose is composed of fibers of carbohydrates. B. Cellulose is an important source of plant fiber for our diet. C. Cellulose is the primary molecule found in wood. D. Cellulose is one of the most abundant organic molecules on Earth. E. Certain animals like ourselves can easily digest cellulose and use it as a source of energy.
Describe alternation of generations. Include in your discussion the following terms: gametophyte, sporophyte, diploid,
haploid, dominant form, meiosis, and fertilization. What will be an ideal response?
Which of the following pairs is mismatched?
A) Propionibacterium — Swiss cheese B) Penicillium — blue cheese C) Lactobacillus — yogurt D) Acetobacter — vinegar E) Bacillus — beer
Approximately ________ years ago, atmospheric oxygen reached its current concentration (i.e., ~21 percent)
a. 100–500 million b. 600–900 million c. 1–2 billion d. >2 billion