Which of the following statements about electron microscopes is true?
A) Electron microscopes focus electron beams to create a magnified image of an object.
B) Scanning electron microscopes are used to study the details of internal cell structure.
C) Transmission electron microscopes are mainly used to study cell surfaces.
D) Specimens must be sectioned to be viewed under a scanning electron microscope.
Answer: A
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Imagine that you are investigating the production of insulin in normal cells to help determine the cause of faulty insulin production in cells where insulin appears to be synthesized but fails to be secreted from the cell
You design experiments using three different pharmaceutical compounds to help pinpoint the trouble spot in the protein synthetic pathway. The first compound blocks transport vesicle movement in the cytoplasm. The second blocks the SRP release from the ribosome and mRNA. The third compound binds to and blocks the signal sequence so the SRP cannot recognize it. For each of these three treatments, indicate 1) whether the protein would be made at all, and if so, 2) where in the cell you would find it. What will be an ideal response?
Which of the following statements about the interactions between the hypothalamus and pituitary is false?
a. Most hypothalamic hormones that act on the anterior pituitary are releasers that encourage secretion of hormones by target cells b. The hypothalamus has some neurons whose axons extend into the pituitary's posterior lobe. c. The posterior lobe of the pituitary secretes hormones made in the hypothalamus. d. Antidiuretic hormone (ADH) and oxytocin are synthesized in the cell bodies of neurons in the anterior pituitary.
Weedy plants are characterized by all of the following except
a. rapid growth. b. limited seed production. c. great genetic variability. d. the ability to inhabit a variety of habitats. e. asexual reproduction via root spread.
Which of the following is an example of an aquatic community?
A. fishes, snails, crabs, water, and salinity B. fishes, snails, and crabs only C. both water and salinity D. water only E. salinity only