Each HIV particle possesses a ________ on its surface, called gp120, that precisely binds to a protein, called CD4, that is found on the surfaces of the immune system cells called macrophages and T cells.
A. glycoprotein
B. phospholipid
C. polysaccharide
D. glycolipid
E. nucleic acid
Answer: A
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A pine tree is a(n) ____, and a pine cone is a(n) ____
a. angiosperm; a seed b. haploid plant body; dipold plant body c. sporophyte; a gametophyte d. gametophye; a sporophye e. egg; pollen grain
Biotechnology has led to important improvements in agriculture. The creation of herbicide and insect-resistant crops has had which of the following effects?
a) decrease in the health risks of consuming farm-grown food b) reduction in the environmental and financial costs of producing food c) increase in susceptibility to soil-welling bacteria d) reduction in the vitamins present in foods such as rice e) increase in the safety of genetically modified foods
In human females, the ovarian cycle begins when...
What will be an ideal response?
Your study buddy is frustrated. "This book says that a single gene can make mice exhibit a certain behavior. That's ridiculous! How can you build any kind of neural circuit with just one gene?" What is your response?
A. "Some genes are longer than others, over 1000kb -- they have enough information to encode a full neural circuit." B. "What the book really means is: all else being equal, one variant of a gene is associated with higher levels of the behavior than the other variant of the gene. All the other thousands of genes are still needed to develop the brain. But variation in one gene can change how a certain neural circuit will behave." C. "If the book says so it must be true. Ours is not to question why." D. "Mice are a lot simpler than we are, and their brains are smaller. One gene is plenty for them to build a circuit."