What does the symbol "kg" represent in the metric system?

1,000 grams
100 liters
10 meters
1 degree celsius

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

What pattern of migration do whales follow?

Which statement describes a way in which the digestive and excretory systems work together? a. the nephrons absorb nutrients from food going to the large intestine. b. the excretory system balances blood gases in the small intestine. c. the intestinal villi filter blood and send wastes to the bladder. d. the excretory system balances the salts and water obtained from digested food