IIT JEE Practice Question and Answer

Q: How do cancer cells differ from normal cells? 1059 0

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Answer :
Explanation :

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.

Q: 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 x 0 + 1 + 1 = ? 1418 0

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    0
    Correct
    Wrong
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    2
    Correct
    Wrong
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    12
    Correct
    Wrong
  • 4
    10
    Correct
    Wrong
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Answer : 3. "12"
Explanation :

Answer: C) 12 Explanation: Given  1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 x 0 + 1 + 1 Using BODMAS Rule, As multiplication precedes addition, 1 x 0 = 0,  Now, 10 + 0 + 1 + 1 = 10 + 2 = 12.   Hence, 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 x 0 + 1 + 1 = 12.

Q: Nucleic acids are polymers of 1086 0

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    Nucleotides
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    Aminoacids
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    Proteins
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    Wrong
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    Sugars
    Correct
    Wrong
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Answer : 1. "Nucleotides"
Explanation :

Answer: A) Nucleotides Explanation: Nucleic acids are polymers of individual nucleotide monomers. Each nucleotide is composed of three parts: a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Q: What kind of pet always stays on the floor? 1278 0

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    Cat
    Correct
    Wrong
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    Dog
    Correct
    Wrong
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    Carpet
    Correct
    Wrong
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    All of the above
    Correct
    Wrong
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Answer : 3. "Carpet"
Explanation :

Answer: C) Carpet Explanation: A Carpet is the pet which always stays on the floor.

Q: What is the oxidation number of carbon in NaHCO3? 1340 0

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    -4
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    -3
    Correct
    Wrong
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    +4
    Correct
    Wrong
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    +2
    Correct
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Answer : 3. "+4"
Explanation :

Answer: C) +4 Explanation: The given compound is NaHCO3 Sodium bicarbonate which is commonly known as Baking soda. Oxidation numbers are the charges on ions. When a neutral atom loses electrons it becomes positively charged. When a neutral atom gains electrons it becomes negatively charged.   Here the C represents the oxidation state of carbon in this compound. Compounds are electrically neutral, which is why we set the sum of the oxidation states equal to zero. Sodium has a +1 oxidation state. Hydrogen has a +1 oxidation state. Oxygen has a -2 oxidation state. There are three oxygen atoms, which means the total oxidation state provided by both oxygen ions is -6. Adding up these oxidation states we get: 1 + 1 + (-6) + C = 0 -4 + C = 0 => C = 4 This means the oxidation state of carbon in this compound is +4.

Q: Dry ice is nothing but 2097 0

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    Solid carbon dioxide
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    Baking soda
    Correct
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    Gaseous carbon dioxide
    Correct
    Wrong
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    Carbon monoxide
    Correct
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Answer : 1. "Solid carbon dioxide"
Explanation :

Answer: A) Solid carbon dioxide Explanation:   Dry ice is solid form of carbon dioxide, used as a cooling agent.   It lower temperature than that of water ice and not leave any residue.

Q: Anil purchases two books for Rs.100. He sells first at loss of 5% and second al 20% profit. If he gets Overall profit of 5% then what is cost of first book? 1631 0

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    58
    Correct
    Wrong
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    60
    Correct
    Wrong
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    55
    Correct
    Wrong
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    45
    Correct
    Wrong
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Answer : 2. "60"
Explanation :

Answer: B) 60 Explanation: -5-----------------------5-------------------20 5-(-5) = 10 20-5= 15 Ratio of cost price of book1 and book2 = 3:2  Then cost price of book 1 is given by (3/5) x 100 = Rs. 60.

Q: The closest algal relatives of land plants are 1269 0

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    charophytes
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    chrysophytes
    Correct
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    rhodophytes
    Correct
    Wrong
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    bacillariophytes
    Correct
    Wrong
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Answer : 1. "charophytes"
Explanation :

Answer: A) charophytes Explanation: The charophytes are the extant group of green algae that are most closely related to modern land plants.

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