Active transport means the molecules move against a concentration gradient from areas of lower concentration to areas of higher concentration.
They breathe through their skin. Air dissolves on the mucus of their skin, so they MUST stay moist to breathe.
If worms dry out, they suffocate. As fresh air is taken in through the skin, oxygen is drawn into the worm's circulatory system, and the worm's hearts pump the oxygenated blood to the head area.
Answer:
Answer is 2. Fibroblasts fail to divide.
Explanation:
Tissue culture experiment is the experiment where tissues are grown in an artificial medium. This involves the use of growth medium such as agar or broth. This process help to produce needed tissues in a short period of time.
Fibroblasts are cells which are found in the collective tissues, and they produce collagen. The collagen produced by the Fibroblasts play important role in tissue repair. Fibroblasts are regarded as the main cells in the connective tissue.
Note that, PDGF, which is Platelet -derived growth factor in full, is a growth factor regulating cell growth and it's division.
Snake goes to frog frog goes to bug bug goes to leaf and leaf goes to soil
