Which correctly describes crossing over? a.)the process whereby nonsister chromatids exchange genetic material
b.)the process whereby homologous chromosomes are pulled to opposite poles of the cell
c.)the process whereby sister chromatids are pulled to opposite poles of the cell
d.)the process whereby homologous chromosome pairs align randomly along the metaphase plate

After reading the paragraph below, answer the questions that follow. researchers have created a robot that has a very thin leg that is moved by cardiac (heart) cells contracting in unison. the robot, made of a polymer similar to that used in making contact lenses, is bathed in heart cells with supporting cells, which then attach to the robot and provide movement as they contract. all of the cardiac cells working together can cause the robot leg to move in a way that individual cells could not. this is an example of a. emergent properties of cells. b. energy flow through an ecosystem. c. adaptation. d. internal environment regulation.

Will mark branliest. the theory of plate tectonics was developed with the contribution of scientists from many different disciplines. which of the following is a contribution from geophysicists?

The nervous system interacts with the endocrine system by a. using hormones as connections b. sending nerve impulses directly to glands c. using neuroendocrine cells as connections d. sending neurotransmitters directly to neurons