Questions

Charles Macintosh (29 December 1766 – 25 July 1843) was a Scottish chemist and inventor of waterproof fabrics.He devoted all his spare time to science, particularly chemistry, and before he was twenty resigned his clerkship to take up the manufacture of chemicals. In this he was highly successful, inventing various new processes. His experiments with one of the by-products of tar, naphtha, led to his invention of waterproof fabrics.

We have 12 months.

In every month we get 28 or more days. 

So that implies we get 28 days in each and every month.

There are many differences between cancer cells and normal cells. Some of the differences are well known, whereas others have only been recently discovered and are less well understood.

Cancer Cells vs. Normal Cells ::

Below are some of the major differences between normal cells and cancer cells, which in turn account for how malignant tumors grow and respond differently to their surroundings than benign tumors.

Growth :—

Normal cells stop growing (reproducing) when enough cells are present. For example, if cells are being produced to repair a cut in the skin, new cells are no longer produced when there are enough cells present to fill the hole; when the repair work is done. In contrast, cancer cells don’t stop growing when there are enough cells present. This continued growth often results in a tumor (a cluster of cancer cells) being formed. 

Communication :—

Cancer cells don’t interact with other cells as normal cells do. Normal cells respond to signals sent from other nearby cells that say, essentially, “you’ve reached your boundary.” When normal cells “hear” these signals they stop growing. Cancer cells do not respond to these signals.

Stickiness :—

Normal cells secrete substances that make them stick together in a group. Cancer cells fail to make these substances, and can “float away” to locations nearby, or through the bloodstream or system of lymph channels to distant regions in the body.

Ability to Metastasize (Spread) :—

Normal cells stay in the area of the body where they belong. For example, lung cells remain in the lungs. Cancer cells, because they lack the adhesion molecules that cause stickiness, are able to travel via the bloodstream and lymphatic system to other regions of the body—they have the ability to metastasize. 

Appearance :—

Under a microscope, normal cells and cancer cells may look quite different. In contrast to normal cells, cancer cells often exhibit much more variability in cell size—some are larger than normal and some are smaller than normal. In addition, cancer cells often have an abnormal shape, both of the cell, and of the nucleus (the “brain” of the cell.) 

The rate of growth :—

Normal cells reproduce themselves and then stop when enough cells are present. Cancer cells reproduce rapidly before the cells have had a chance to mature.

Maturation :—

Normal cells mature. Cancer cells, because they grow rapidly and divide before cells are fully mature, remain immature. Doctors use the term undifferentiated to describe immature cells (in contrast to differentiated to describe more mature cells.) 

Evading the immune system  :—

When normal cells become damaged, the immune system (via cells called lymphocytes) identifies and removes them. Cancer cells are able to evade (trick) the immune system long enough to grow into a tumor by either by escaping detection or by secreting chemicals that inactivate immune cells that come to the scene.

Functioning :—

Normal cells perform the function they are meant to perform, whereas cancer cells may not be functional. For example, normal white blood cells help fight off infections. In leukemia, the number of white blood cells may be very high, but since the cancerous white blood cells are not functioning as they should, people can be more at risk for infection even with an elevated white blood cell count.

The central nervous system ( brain and spinal card ) are invested with the meninges which nourish and protect the system .This again is enclosed inside a bony box which has the skin above it

Yes, you are requested to write an essay as part of your TOEFL iBT exam. There are 5 major types for TOEFL essay topics. They are:

1. Agree or Disagree

2. Preference

3. Description / Explanation

4. If / Imaginary

5. Compare & Contrast

The best way to prepare for this essay writing is to understand the writing style clearly. To understand the the genre, you can refer some sample essays submitted before by different contestants. You can get such sample TOEFL essays from various sources such as TOEFL training websites, cheap essay writing service sites, online libraries, etc. Once you are well aware of the writing pattern the next thing is to practice writing random essays. Keep in mind that you should practice writing essays of all above mentioned 5 types. If you make it a routine to write random essays, gradually you can compete at higher level to write the given essay topic for your TOEFL iBT exam.