93' SBIOA Exam

PART A:  MULTIPLE CHOICE.  THERE IS AN ANSWER PAGE FOR THESE QUESTIONS.  USE IT.

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11 .   During the growth of a tomato plant from a seed, it increases considerably in biomass.  Which of the following  materials, obtained from the environment, are necessary for the growth and increase in biomass?

       a .         carbon dioxide and water

       b .         water, nitrate, and methane

       c .         carbon dioxide, oxygen, and nitrogen

       d .         *correct*water, carbon dioxide, and mineral salts

       e .         mineral salts, carbon dioxide, and oxygen

12 .   The rate of growth of a natural population

       a .         always reaches the carrying capacity of the ecosystem.

       b .         when graphed, always has a positive slope.

       c .     *correct*is limited by the carrying capacity of the ecosystem.

       d .    is calculated by subtracting death rate from birth rate.

       e .         exceeds the death rate and rate of emigration.

13 .   The current fluid mosaic model of the cell membrane was devised to account for all the following observations EXCEPT one.  Which one is NOT part of the model?

       a .         Phospholipids molecules are aligned with their fatty acid tails in the centre, and their phosphate heads towards the outside.

       b .         Integral (intrinsic) proteins are interspersed through the phospholipid bilayers.

       c .         Integral (intrinsic) proteins move from place to place in the membrane.

       d .         Phospholipid bilayers are flexible and somewhat fluid.

       e .         *correct*Peripheral (extrinsic) proteins move in the space between the bilayers

14 .   In the process of fermentation, glucose is broken down into carbon dioxide and alcohol, with the evolution of some energy.  With respect to this process, it can also be said that,

       a .         *correct*entropy is increasing as the reaction takes place.

       b .         entropy is being converted into free energy.

       c .     the reaction violates the second law of thermodynamics.

       d .    the free energy of tghe system is increasing.

       e .    the released energy is eventually used to produce more glucose.

15 .   `Free energy' is

       a .    *correct* energy that can do useful work.

       b .    energy which is released in every chemical reaction.

       c .     energy released during endergonic reactions.

       d .    the total energy involved in a chemical reaction.

       e .    heat energy.

16 .   The second law of thermodynamics states that as entropy increases, free energy

       a .         remains constant.

       b .         *correct*decreases.

       c .         depends on the chemical reaction involved.

       d .         varies inversely with the absolute temperature.

       e .    is released as heat energy.

17 .   Proteins are to ribosomes as ATP is to the

       a .         chromosomes.

       b .         centrioles.

       c .         Golgi apparatus.

       d .         *correct*mitochondria.

       e .         nucleus.

18 .   How many guanine bases are present in a DNA molecule 1000 nitrogen base pairs long, if 20% of the molecule consists of adenine molecules?

       a .    *correct* 600

       b .    300

       c .     400

       d .    200

       e .    800

19 .   If the base sequence in DNA is AATCGG, what is the sequence of the complementary chain?

       a .    TTGCAA

       b .    CCATUU

       c .     *correct* TTAGCC

       d .    UUAGCC

       e .    TTUGCC

20 .   One difference between DNA and RNA is that

       a .    *correct*the carbohydrate parts of the two molecules differ.

       b .    the positions of the phosphate bonds differ.

       c .     DNA contains nucleotides while RNA has nucleosides.

       d .    DNA contains guanine and RNA does not.

       e .    RNA forms a double helix while DNA is single.

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