What is a chemical element essential for good health?
Options:
- (A) sweating
- (B) light energy
- (C) oxygen
- (D) bioaerosols
- (E) Chlorophyll
- (F) hydration
- (G) Potassium
- (H) fever
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Let's think first: Minerals are chemical elements that are essential for body processes. Potassium is a trace mineral essential for growth and good health. Potassium is a chemical element essential for good health.... So the answer is [(G)]

What can be part of invading a host?
Options:
- (A) It helps them survive
- (B) Something that causes allergies
- (C) Movement of an air mass
- (D) energy of moving objects
- (E) vascular conncectivity
- (F) harmful substances
- (G) Leptospirosis
- (H) competing for resources
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Let's think first: Fungi have special structures for penetrating a host. Host tissue penetration occurs to the point of vascular connectivity. Fungi can invade a host to the point of vascular conncectivity.... So the answer is [(E)]

What increases the productivity and stability of the entire global system?
Options:
- (A) important habitats
- (B) Plants growth
- (C) solar system
- (D) animals
- (E) biodiversity
- (F) environment
- (G) bottlenecks
- (H) power stations
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Let's think first: Biodiversity increases the productivity and stability of ecosystems. Marine ecosystems also act as stabilizers of global systems especially our climate. Biodiversity increases the productivity and stability of the entire global system.... So the answer is [(E)]

Vertebrate chordates have what part of the skeletal system?
Options:
- (A) spinal column
- (B) hard bones
- (C) aerobic capacity
- (D) cartilage bones
- (E) critical organs
- (F) joints
- (G) fur and fat
- (H) graptolites
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Let's think first: Vertebrate chordates have a backbone. Invertebrates are animals who lack a backbone or spinal column. Vertebrate chordates have a spinal column.... So the answer is [(A)]

Some what which live off a host kill it, but most do not?
Options:
- (A) offspring
- (B) pets
- (C) poisons
- (D) fungi
- (E) Leptospirosis
- (F) bacteria
- (G) animals
- (H) organisms
--
Let's think first: Some parasites kill their host, but most do not. Parasites are organisms which live off a host. Some organisms which live off a host kill it, but most do not.... So the answer is [(H)]

What are a major food source for other organisms, including humans?
Options:
- (A) Earthworms
- (B) Soft-bodied invertebrates
- (C) Fully cooking the oysters
- (D) absorb light energy
- (E) remains of prehistoric life
- (F) members of their own species
- (G) Humans
- (H) Lawns
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Let's think first: Mollusks are a major food source for other organisms, including humans. Mollusks are soft-bodied invertebrates. Soft-bodied invertebrates are a major food source for other organisms, including humans.... So the answer is [(B)]