Which of the following animals has a single-loop closed circulatory system:

a. fish
b. frog
c. human
d. crocodile

Which strategy is an example of how companies may upgrade themselves to meet changing customer preferences? a.doing door-to-door sellingb.using billboards to advertise the productsc. making online shopping services availabled.giving discounts on products

Which sentence best describes the relationship between chlorophyll and the chloroplast? a.) chlorophyll is a chemical found in a chloroplast. b.) chloroplast is a chemical found in a chlorophyll. c.) both chlorophyll and chloroplasts are found in animals. d.) both chlorophyll and chloroplasts make carbon dioxide.

Substances that can pass through cell membranes by diffusion include a. na ions. b. proteins c. glucose. d. oxygen.