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1. A virus is a non-living pathogen that cannot reproduce outside of the cells of an
infected organism.
2. HIV attacks and cripples the immune system, invades macrophages and helper T
cells, and kills large numbers of helper T cells. A person infected by HIV might
develop the disease called AIDS, have viruses reproducing in helper T cells, & be
more susceptible to a variety of pathogens.
3. The debilitating effects of AIDS are caused by the inability of the immune system
to activate B cells and cytotoxic T cells, produce antibodies against pathogens,
and recognize and destroy infected cells.
4. Infections generally result in an increase in the number of white blood cells.
5. Secondary exposure to a pathogen results in very rapid production of antibodies,
stimulates memory cells to divide quickly, & may result in destruction of the
pathogen before the person knows he or she is infected.
6. Antibodies are the Y-shaped molecules that are produced by plasma cells upon
exposure to a specific antigen and can bind to that antigen.
7. Vaccines are produced from killed or weakened pathogens.
8. The immune system recognizes vaccine agents as foreign, destroys them, and
"remembers" them. When the virulent version of an agent comes along the body
recognizes the protein coat on the virus, and thus is prepared to respond, by (1)
neutralizing the target agent before it can enter cells, and (2) by recognizing and
destroying infected cells before that agent can multiply to vast numbers.
9. The skin is a nonspecific defense against pathogens. The skin provides protection,
sensation of heat and controls body temperature.
10. Organisms that manufacture organic nutrients for an ecosystem are called primary
producers. When an organism dies, the nutrients in its body are released by the
action of decomposers. In a food web, decomposers receive energy from every
other type of organism. Fungi and bacteria are decomposers. Organisms that
complete the final breakdown and recycling of organic materials from the remains
or wastes of all organisms are decomposers. An ecosystem can survive without
consumers.
11. A relationship between a producer and consumer is best illustrated by a zebra
eating grass.
12. Animals that feed on plants are at least in the 2nd trophic level.
13. Photosynthetic organisms such as algae, are examples of producers in an
ecosystem.
14. The sum total of the different kinds of organisms in an ecosystem is its
biodiversity.
15. The number of trophic levels in an ecological pyramid is limited by the amount of
energy that is lost at each trophic level.
16. Precipitation and evaporation are important components of the water cycle.
17. The commonality among the C cycle, N cycle & water cycle is that the substance
is required by all living things and is involved in many processes that occur in all
living things.
18. Transfer of carbon between organisms depends primarily on photosynthesis and
cellular respiration.
The nitrogen cycle includes conversion of atmospheric nitrogen into usable
organic compounds by bacteria, conversion of nitrogen from decaying organisms
into ammonia, & nitrogen fixation.
19. Circulation provides your body with oxygen, nutrients, and a way to get rid of
waste.
20. Forelimbs of humans, bats, alligators, and penguins are homologous structures.
The similarity of these structures suggests that the organisms have a common
ancestor.
21. Neurotransmitters are released at synapses.
22. Hormones are essential to maintaining homeostasis mainly because they cause
specific responses in specific cells.
23. An increase in the hormone glucagon raises the blood sugar level.
24. The actual exchange of gases occurs at the site of the alveoli.
25. Gray matter consists of cell bodies of neurons.
26. The spinal cord is linked to the peripheral nervous system through spinal nerves.
27. A disadvantage of nervous signals, which is not true of hormonal messages, is
that the effects of nervous signals last for only a short time.
28. The heart and the blood vessels are separate organs that form the circulatory
system.
29. When a neuron is not sending a signal, it is "at rest." When a neuron is at rest, the
inside of the neuron is negative relative to the outside. At rest, there are relatively
more sodium ions outside the neuron and more potassium ions inside that neuron.
Potassium ions are most concentrated inside the cell.
30. Motor neurons transmit messages from the central nervous system to a muscle or
gland.
31. All endocrine glands secrete hormones directly into the bloodstream or fluid
around cells.
32. Secondary exposure to a pathogen results in very rapid production of antibodies,
stimulates memory cells to divide quickly, & may result in destruction of the
pathogen before the person knows he or she is infected.
33. “Antennae” that extend from a neuron and that receive information from other
cells are called dendrites
34. The peripheral nervous system provides pathways to and from the central nervous
system.
35. Natural selection is the process by which organisms with traits well suited to their
environment survive and reproduce at a greater rate than less well-adapted
organisms in the same environment.
For ex., If a mutation introduces a new skin color in a lizard population, the
frequency of the new allele will increase if the mutation makes some lizards more
fit for their environment than other lizards
36. When an impulse moves down the axon, a small part of the axon momentarily
reverses its polarity.
37. “Antennae” that extend from a neuron and that receive information from other
cells are called dendrites.
38. Hormones react to stimuli from outside the body, coordinate the production and
use of energy, and maintain nutrition and metabolism.
39. Demography is NOT one of the factors that play a role in population growth rate.
When organisms move out of the population, this is known as emigration. If
immigration and emigration numbers remain equal, the most important
contributing factor to a slowed growth rate is decreased birthrate.
40. Natural selection acts directly on phenotypes. Natural selection causes changes in
the frequency of certain alleles in a population.
41. The process by which a species becomes better suited to its environment is known
as adaptation.
42. Mutations are a source of new genetic material.
43. The type of genetic drift that follows the colonization of a new habitat by a small
group of individuals is called the founder effect.
44. The separation of populations by barriers such as rivers, mountains, or bodies of
water is called geographic isolation. The geographic isolation of 2 populations of
a species tends to increase differences between their gene pools because it
prevents interbreeding between the populations.
45. Recessive alleles that cause deadly diseases are not completely removed from the
gene pool because they are carried in heterozygous individuals.
46. A species is more likely to survive in a changing environment if the species has a
lot of genetic diversity.
47. A community that will likely have some member species survive a major change
in the environment is likely to have high biodiversity.
48. A digestive enzyme in saliva that breaks sown starch into sugar is amylase.
49. Reflex arcs are nerve signals that involve only 2 synapses so the body reacts
quickly to a stimulus.