After the third dose -- given at age 6 months -- your child will be 80% to 85% immune to whooping cough for 3 to 5 years. Everyone -- including adults -- from age 11 up should receive a booster vaccine, called Tdap. It's a combined tetanus, diphtheria, and pertussis booster vaccine.
How many chromosomes are in the nucleus of an onion root cell? There are 8 chromosomes in the nucleus of an onion root cell. The cells are undergoing mitosis, during which the amount of DNA is doubled even as the number of chromosomes â¦ remains constant. How many chromosomes do onions have?
Mitosis in the Onion Root-tip. The onion root tip is one of the most widely used materials for the. study of the cell cycle because it is readily available, preparation of. the dividing cells is easy, and the chromosomes are large and few in. number, hence, easier to study than the cells of many other. organisms.