This phylum of vascular, seed-bearing plants is limited to one living species. That species is a
deciduous tree with fan-shaped leaves. It has separate male and female plants, and the males are often
planted in cities because of their resistance to pollution, insects, and disease.
a. Cycadophyta
b. Anthophyta
c. Gnetophyta
d. Coniferophyta
e. Ginkgophyta
E
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In the United States, every clinical and research institution requires that workers be protected from ________ that is contracted almost exclusively from handling patient specimens (rather than from known exposure or accidents)
A) anthrax B) hepatitis B C) drug-resistant mycobacteria D) influenza
Clostridium botulinum typically does not produce its toxin under conditions that are
A. anaerobic. B. alkaline. C. neutral. D. acid.
Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large, complex, undigested lipids. Which cellular organelle must be involved in this condition?
A) the endoplasmic reticulum B) the Golgi apparatus C) the lysosome D) mitochondrion
The image below diagrams the action of an enzyme. Notice that the enzyme is depicted as being more tightly wrapped around the substrates in step 2 than it is in step 1. Why is this?
a. When a substrate locks into the active site of an enzyme, the enzyme changes shape to mold itself around the substrates. b. Generally, the size of a substrate is larger than the size of the active site into which it must fit. When the substrate enters the active site, the active site must stretch to fit. c. Before catalysis can occur, a substrate must change its shape so that it fits into the active site of the enzyme more precisely. d. Most active sites are only designed to hold one substrate. In this image, two substrates enter the active site, creating a tighter fit.