What lacks walls and membranes?
Options:
- (A) deserts
- (B) flower cells
- (C) viruses
- (D) fungi
- (E) tree cells
- (F) bacteria
- (G) plant cells
- (H) alpacas
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Let's think first: Viruses are not cells. Plant cells are surrounded by a cell membrane and a cell wall. Viruses do not have walls and membranes.... So the answer is [(C)]

What happens to genes located on the same chromosome
Options:
- (A) metabolic reaction
- (B) production of energy
- (C) produce offspring
- (D) female sex cells
- (E) The flowers are pollinated
- (F) They are inherited together
- (G) Earth orbiting the Sun
- (H) a hemisphere is tilted away from the sun
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Let's think first: Genes that are located on the same chromosome are called linked genes. Linked genes are inherited together. Genes that are located on the same chromosome are inherited together.... So the answer is [(F)]

The gene pool expands through fertilization and:
Options:
- (A) offspring
- (B) agriculture
- (C) mutation
- (D) babies
- (E) seeds
- (F) zygotes
- (G) relocation
- (H) competition
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Let's think first: Mutation creates new genetic variation in a gene pool. Fertilization increases genetic variation. Mutation and fertilization have similar effects on the gene pool.... So the answer is [(C)]

How do children learn?
Options:
- (A) reusing materials
- (B) allow growth
- (C) by lying
- (D) Riding a bike
- (E) in many ways
- (F) exercise
- (G) by sleeping
- (H) just one way
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Let's think first: Playing is just one of many ways that mammals and other animals learn how to behave. Children learn through play and in other ways. Children and animals learn in many ways.... So the answer is [(E)]

Many _ can cause the immune system to not work properly.
Options:
- (A) fever
- (B) bacteria
- (C) radiation
- (D) fungi
- (E) A drug.
- (F) Allergies
- (G) cancers
- (H) Toxicity
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Let's think first: Immunodeficiency occurs when the immune system is not working properly. Many cancers can cause immunodeficiency. Many cancers can cause the immune system to not work properly.... So the answer is [(G)]

How many types can viruses infect?
Options:
- (A) mice
- (B) pigs
- (C) bird
- (D) RNA
- (E) ova
- (F) tiny
- (G) HPV
- (H) Two
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Let's think first: Viruses often infect bacteria. Bacteria are normally classified as either 'good' bacteria or 'bad' bacteria. Viruses can infect good and bad types.... So the answer is [(H)]