Line 1: *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.*
*(D)*
Line 2: *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*

Logic of a solution: *Trees have woody stems covered with bark. On the outside is a protective skin of bark made mainly of cork. Trees have woody stems covered with protective skin.*
*(C)*
The original question: *Trees have woody stems covered with what?
Options:
- (A) heat energy
- (B) thin skin
- (C) protective skin
- (D) skinny cells
- (E) white skin
- (F) Chlorophyll
- (G) Organic compounds
- (H) looseness*

Line 1: *Excretion is the process of removing wastes and excess water from the body. Ketones are exhaled and excreted in urine. Urination is a process of removing wastes and excess water from the body.*
*(B)*
Line 2: *What is a process of removing wastes and excess water from the body?
Options:
- (A) hydration
- (B) urination
- (C) incontinence
- (D) trash can
- (E) vaporization
- (F) Cooking
- (G) body waste
- (H) Exfoliation*

Logic of a solution: *Air pollution harms the respiratory and circulatory systems. Cars are a significant source of air pollution. Cars harm the respiratory and circulatory systems.*
*(D)*
The original question: *What harms the respiratory and circulatory systems?
Options:
- (A) oil
- (B) rain
- (C) sulfur
- (D) cars
- (E) tires
- (F) coal
- (G) tar
- (H) bicycles*

Line 1: *Viruses contain DNA but not much else. DNA is short for Deoxyribonucleic Acid. Viruses contain deoxyribonucleic acid but not much else.*
*(H)*
Line 2: *What contains an abundance of deoxyribonucleic acid and not much else?
Options:
- (A) Conifers
- (B) PDAs
- (C) pollen
- (D) anemia
- (E) bacteria
- (F) proteins
- (G) diseases
- (H) viruses*

Line 1: *Biodiversity generally increases from the poles to the equator. Most rainforests lie near the equator. Biodiversity generally increases from the poles to the area where the rainforests lie.*
*(E)*
Line 2:
*Biodiversity generally increases from the poles to the area where what is found?
Options:
- (A) animals
- (B) Fjords
- (C) Most plants
- (D) Icebergs
- (E) Rainforests
- (F) Tundra
- (G) our planet
- (H) Animal survival*