Fact 1: Migration is a type of movement that changes population size. Fact 2: Bird Migration and Isotopes Tracking animal migration is a difficult task. Given the two facts above, what undergoes a movement that changes population size?

OPTIONS:
- Wasps
- camels
- sheep
- insects
- animals
- sharks
- birds
- ducks

Answer: birds

Fact 1: Organs of excretion make up the excretory system. Fact 2: Excess estrogen is excreted in the bowel. Given the two facts above, what helps make up the excretory system?

OPTIONS:
- sugar
- gills
- h2o
- lungs
- aorta
- bowel
- fungi
- honey

Answer: bowel

Fact 1: Thick fur can be used for keeping warm. Fact 2: If Arctic foxes are in too cool weather, they warm up by their thick fur. Given the two facts above, how do foxes warm up?

OPTIONS:
- ligt
- coat
- fur
- skin
- two
- water
- fats
- air

Answer: fur

Fact 1: Ejaculation occurs when muscle contractions propel sperm from the epididymes. Fact 2: An ejaculation occurs as the muscles around the prostate gland and the penis contract. Given the two facts above, what happens when muscles around the prostate gland contracts?

OPTIONS:
- preventing heat transfer
- The bending of a ray of light
- Generating heat
- Warm air moving into cold air
- Sperm leaves the epidiymes
- heat produced
- Release energy
- rapid expansion

Answer:
Sperm leaves the epidiymes