1. Which of the following is required for active transport to occur across a cell membrane?  * A. 
a concentration gradient
* B. 
a storage vacuole
* C. 
energy
* D. 
water

Which of the following statements is true? a. there are more chromosomes in an organism than there are genes. b. there are more genes in an organism that there are chemical bases. c. dna is made of sugar, phosphate, and carbon. d. genes are found in specific locations on a chromosome.

The theories on the expansion of galaxies maybe re-examined to strengthen science should not be tested to strengthen science will weaken scientific knowledge if they change will become laws if they don't change

Imagine a person stepping on a pin and pulling his or her foot away. look at the reflex arc of this scenario below. which statement best describes the image? a)the sensory nerve carries the signal from the effector to the interneuron, and the motor neuron carries the signal to the receptor. b)the motor nerve carries the signal from the receptor to the interneuron, and the sensory neuron carries the signal to the effector. c)the sensory nerve carries the signal from the receptor to the interneuron, and the motor neuron carries the signal to the effector. d)the sensory nerve carries the signal from the receptor to the motor neuron, and the interneuron carries the signal to the effector.