Chemical digestion involves breaking down the nutrients into smaller cells
Physical digestion is using physical movements such as chewing and swallowing
The stage at which the development of the brain reaches its adult is the middle childhood. A child's Brain undergoes a period of development from birth to three-producing more than a million neural connections each second. This development is influenced by many factors, which include the child's relationships, experiences and environment.
Answer:
Mechanical barriers — which include the skin , mucous membranes , and fluids such as tears and urine — physically block pathogens from entering the body. Chemical barriers — such as enzymes in sweat , saliva , and semen — kill pathogens on body surfaces.
The answer is <span>the number of DNA mutations in an organism is measured over time to determine how long it will take for a new species to evolve.</span>