Answer:
Harmful Mutations A genetic disorder is a disease caused by a mutation in one or a few genes. A human example is cystic fibrosis. A... Cancer is a disease in which cells grow out of control and form abnormal masses of cells.Explanation:
Answer: natural selection
Answer:
is about 4.6 billion years old
Oncogenes result from turning on, or activating proto oncogenes. Proto oncogenes are genes that code for positive cell cycle regulators, so proto oncogenes code for proteins that turn on cell division. Proto oncogenes are normal genes, but when they are mutated, they become oncogenes. Oncogenes are expressed too much, which makes them turn on cell division too much, which is cancer.
Answer:
They have helical thickening of lignin in their walls to prevent collapse
Explanation:
the primary function of Xylem and its conducting vessels tracheids is to provide support and tranport water and minerals in plants.
Xylem vessels have layers of dead materials in the walls called LIGNIN. Lignin is a polymer; a very strong, hard materials that stop water passage through it,because it contains dead cells,
Therefore the presence of deposit of these strong impermeable, ligified walls in its walls prevent its collapse during mass flow of water of transpiration pull.
