The fusion of the sperm with the egg results in the formation of a zygote that develops into a new offspring. Twins refers to the two offspring which are a result of the same pregnancy. They are of two types. Monozygotic twins are a result of the single zygote (formed by the fusion of one egg with a single sperm) spiltting into two embryos forming the identical twins. Dizygotic twins are a result of two eggs fertilized with two different sperms forming the fraternal twins.
Identical twins are genetically simliar. The genetic material is derived from the same embryo and thus, the DNA of the identical twins are nearly identical. The spilitting of the embryo formed results in the separation of the same genetic material or identical DNA getting incorporated into the twins making them look alike in majority of the cases.
Answer:
The problems that can be caused by Expansion or Contraction a;long with the solutions are:
Explanation:
- The railway tracks made of steel expand during the summer and contract during the winter. This can cause them to become curved during the summer thereby causing rail derailment.In order to prevent this, an air gap is kept in between the railway lines so that they get the space to expand without getting curved.
- The electric wires linking the telegraph posts are made up of metals and so they expand in the summer and contract in the winter, which can cause them to tear. This is why the wires are loosely fixed so that they can expand and sag in the summer and contract and tighten in the winter.
- Bridges are constructed with joints where some space is maintained to allow the easy expansion and contraction in summer and winter respectively.
Answer:
It destroy both harmful and beneficial microbes.
Explanation:
If scientist added a chemical to destroy the arctic microbes, the beneficial as well as harmful microbes also eliminated from that area where chemical is applied. The removal of harmful microbes is a good thing but the removal of beneficial microbes brings instability in the environment. These beneficial microbes helps in the recycling of nutrients for the plants present there. So the negative effect of chemical is that it also effect the beneficial microbes which are necessary for the ecosystem.
Answer:
Cerebral Nuclei.
Explanation:
Cerebral nuclei refers to one of three components of the cerebrum. It is a composite structure of the end-brain defined on the basis of origin from the ventricular ridge of the embryonic Encephalon. It is a lusters of gray matter that contain neuron cell bodies and lie within masses of white matter.
