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?
This onion root tip plant cell is in metaphase of mitosis. Replicated chromosomes (chromatids) are lined up on the equator of the cell and are attached to the spindle fibers. The spindle along with the spindle fibers are evident. Ed Reschke/Photolibrary/Getty Images.