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?
Humans have 23 pairs of chromosomes, for a total of 46 chromosomes. In fact, each species of plants and animals has a set number of chromosomes. A fruit fly, for example, has four pairs of chromosomes, while a rice plant has 12 and a dog, 39. Top of page.