Answer:
External factors include physical and chemical signals. Growth factors are proteins that stimulate cell division. – Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.
Explanation:
From Google
Answer:
Have different numbers of neutrons
Explanation:
Isotopes of an element have different atomic numbers because thy differ in neutron number even though proton number remains the same across the isotopes. The mass number is the summation of the proton and neutron number. Phosphorus has approximately 23 isotopes whose mass number range between 25 and 47. Only ³¹P is stable.
Answer:
kind is a group of living things with certain similar characteristics
Explanation:
The skeletal system supports and protects the body and the muscular system is for movement.
True because some fossils only lived in certain places
