Have you ever seen the Ghost Rider
Answer:
It's a form of asexual reproduction!
Development of the offspring happens without fertilization in this type of reproduction.
The two main ways in which parthenogenesis happens is by apomixis or automixis. Through apomixis , the egg cells are produced by mitosis. Through In automixis, egg cells are produced by meiosis.
Mitosis = a part of cell cycle: replicated chromosomes are separated into 2 nuclei
Meiosis = type of cell division that reduces the chromosome number by half. So now there is four haploid cells that are genetically distinct from their parent cell.
Example:
An example of an animal that can use this reproduction is a bonnethead shark! Once a shark had a baby in a tank that only had three females!
(read about that on wikipedia)
Answer:
True
Explanation:
B cells are B lymphocytes and are one of the types of white blood cells. Their main role is in the acquired immune system in which they help in the humoral immune response of the body by the secretion of antibodies. The maturation of the B cells occurs in the bone marrow in mammals. But in birds, these cells mature in an organ named bursa of Fabricius which is a lymphoid organ in birds. These B cells were first isolated form the bursa of Fabricius of the birds.
Answer:
The correct option is A. they evolved from land mammals.
Explanation:
Evolution can be described as a process through which organisms in a species change over a period of time due to the natural selection of the environment. Those organisms that have many similarities in their functions or structures are considered closer to one another and have the same common ancestors.
The properties mentioned in the question about cetaceans resembles the properties of land mammals. For example, cetaceans lack gills and breathe air. Land mammals also do not have gills and need to respire for living. The cetaceans have fin bones which are similar to the limb bones in the land mammals. Hence, these observations show that cetaceas have evolved from land mammals.
