What can be determined by the average number of people per one unit of area?
Options:
- (A) hygeine
- (B) emissions
- (C) animals
- (D) growth
- (E) forces
- (F) health
- (G) education
- (H) people
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Let's think first: Population density is the average number of individuals per unit of area or volume. Another measure of growth is population density. Growth of an area can be determined by the average number of people per unit of area.... So the answer is [(D)]


Organelles that come in pairs are involved in what?
Options:
- (A) movement
- (B) Veins and arteries.
- (C) competition
- (D) Plants growth
- (E) Animal survival
- (F) cell division
- (G) an organism's body
- (H) Plant reproduction
--
Let's think first: Centrioles are organelles involved in cell division. Centrioles come in pairs. Organelles that come in pairs are involved in cell division.... So the answer is [(F)]


Which is the most likely cause of throat tumors?
Options:
- (A) cigars
- (B) Allergies
- (C) viruses
- (D) Pesticides
- (E) rocks
- (F) doctors
- (G) the skin
- (H) water
--
Let's think first: Some viruses can cause cancer. Lung cancer is a formation of tumors in the lung. Some viruses result in the formation of malignant tumors.... So the answer is [(C)]


What causes cell walls to relax?
Options:
- (A) exercise
- (B) sweating
- (C) adding heat
- (D) Energy
- (E) dilation
- (F) heat or cold
- (G) heat
- (H) Dehydration
--
Let's think first: Dilation occurs when cell walls relax. When oxygen level decreases, dilatation of the blood vessels occurs. Decreased oxygen levels cause blood vessels to dilate and cell walls to relax.... So the answer is [(E)]


Invertebrates can be what?
Options:
- (A) people
- (B) scarce resources
- (C) vertebrates
- (D) deposit feeders
- (E) Catch prey
- (F) major threat to health
- (G) more abundant
- (H) planets
--
Let's think first: Earthworms are important deposit feeders that help form and enrich soil. Earthworms by Casey Earthworms are invertebrates. Invertebrates can be deposit feeders.... So the answer is [(D)]


What is something missing in starfish?
Options:
- (A) the body's largest organ
- (B) centralized nervous system
- (C) characteristics
- (D) layers of fat
- (E) permineralization
- (F) biological diversity
- (G) kinetic energy
- (H) A compound that donates proton
--

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Let's think first: Echinoderms lack a centralized nervous system. Echinoderms are represented by the starfish. Starfish lack a centralized nervous system.... So the answer is [(B)]