question: Where does a starfish have its water vascular system?
Options:
- (A) salt and water.
- (B) Chlorophyll
- (C) the environment
- (D) in its arms
- (E) on the rocks
- (F) in its eyes
- (G) Epidermis
- (H) in the ocean
answer: Echinoderms have a unique water vascular system with tube feet. Each starfish arm is lined with tube feet. Each starfish arm contains part of the water vascular system.
The answer is (D)

question: If a tumor has formed, this gene might have mutated:
Options:
- (A) p53
- (B) SNPs
- (C) OCA 2
- (D) DNA
- (E) gene
- (F) tRNA
- (G) malignancy
- (H) TRH
answer: Cells that divide uncontrollably may form a tumor, or abnormal mass of cells. When p53 is mutated, cells divide uncontrollably. When p53 is mutated a tumor may form.
The answer is (A)

question: Why does life continue?
Options:
- (A) to use resources
- (B) organisms produce offspring.
- (C) sub-units of species
- (D) things don't die
- (E) the Earth being tilted
- (F) production of energy
- (G) to keep going
- (H) by keeping them warm
answer: Reproduction is the process by which organisms give rise to offspring. Life continues because of reproduction. Life continues because organisms give rise to offspring.
The answer is (B)

question: What does the substance that male dogs have in urine to mark their territory do?
Options:
- (A) sweating
- (B) attract females
- (C) Release energy
- (D) repels females
- (E) attract enemies
- (F) attract males
- (G) adding heat
- (H) dangerous
answer:
Male dogs use pheromones in urine to mark their territory. Males produce 'pheromones' to attract females. Male dogs use something that attracts females in urine to mark their territory.
The answer is (B)