C. hypothesis. He is giving a possible answer to the question "why did the celery crisp when placed in water?"
From what I googled, in the interior of a cell wall there is a cell membrane
D. Cell Membrane
Answer:the component materials and their arrangement
Explanation:
Bone are important for movement in animals.bones is made up of 15% water,30% collagen fibres and 55% mineral salts..bone cells are widely separated. The Collagen makes bones soft and flexible. Mineral salts makes it fragile and strong.
The osteogenic cells builds the bones and the osteoclasts breaks down older bone tissue, in order to keep the body strong.
Spongy bones contains tiny spicules that helps in strength.
It also reduces the weight of the bones .
The cells of Compact bones are arranged in the direction of stress to keep the bone strong.
They are constantly changing throughout life
The cells of the CNS are called neurons. They secrete neurotransmitters.
