Carbon monoxide, a product of furnaces and engines, is a:
Options:
- (A) acid
- (B) CO2
- (C) kill
- (D) harm
- (E) gas
- (F) form
- (G) CO 2
- (H) HPV
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Let's think first: Carbon monoxide is a gas produced by furnaces and other devices that burn fuel. Fuel is burned inside the engine. Carbon monoxide is a gas produced by furnaces and other engines.... So the answer is [(E)]

What is the process of breaking down food proteins into energy or heat?
Options:
- (A) dissecting
- (B) dehydration
- (C) elimination
- (D) energy
- (E) digestion
- (F) Cooking
- (G) calorie retention
- (H) Evaporation
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Let's think first: Digestion is the process of breaking down food into components the body can absorb. Food proteins are changed into energy or heat to be used or absorbed by the body. Digestion is the process of breaking down food proteins into energy or heat.... So the answer is [(E)]

Hostility can be one outcome of:
Options:
- (A) relocation
- (B) behavior research
- (C) decrease stamina
- (D) forces
- (E) fungi
- (F) competition
- (G) tolerance
- (H) Gunshots
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Let's think first: Competition may lead to aggressive behaviors or displays of aggression. Frequently their behavior is aggressively hostile. Competition may lead to hostility.... So the answer is [(F)]

Fungi spores can multiply through what?
Options:
- (A) natural selection
- (B) trees
- (C) mitosis
- (D) sun's heat
- (E) death
- (F) Conifers
- (G) Deposition
- (H) pregnancy
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Let's think first: Fungi spores can develop into new haploid individuals without being fertilized. Haploid cells multiply asexually through mitosis. Fungi spores can multiply through mitosis.... So the answer is [(C)]

Which chemical controls sexual development and reproduction in females?
Options:
- (A) acetic acid
- (B) Hemoglobin
- (C) Fructose
- (D) barnacles
- (E) animals
- (F) Estrogen
- (G) Pesticides
- (H) Baby spray
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Let's think first: Sex hormones are chemical messengers that control sexual development and reproduction. Estrogens are female sex hormones. Estrogen controls sexual development and reproduction in females.... So the answer is [(F)]

Feathers help what kind of animals fly and provide insulation?
Options:
- (A) preventing heat transfer
- (B) dragons
- (C) passenger pigeons
- (D) butterflies
- (E) animals in the class Aves
- (F) airplanes
- (G) it protects them
- (H) retaining heat
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Let's think first: Feathers help birds fly and provide insulation. Class Aves is for the birds, literally. Feathers help animals in the class Aves fly and give them insulation.... So the answer is [(E)]