HUMAN BIOLOGY

66 Chapter 3

6. Match each organelle with its correct function.
   protein synthesis a. mitochondrion
   movement b. ribosome
   intracellular digestion c. smooth ER
   modification of proteins d. rough ER
   lipid synthesis e. nucleolus
   ATP formation f. lysosome
   ribosome assembly g. flagellum


7. Which of the following statements is not true? Metabolic
   pathways.
   a. occur in a stepwise series of chemical reactions
   b. are speeded up by enzymes
   c. may break down or assemble molecules
   d. always produce energy (such as ATP)


8. Enzymes.
   a. enhance reaction rates
   b. are affected by pH
   c. act on specific substrates
   d. all of the above


9. Match each substance with its correct description.
   a coenzyme or metal ion a. reactant
   formed at end of a b. enzyme
   metabolic pathway c. cofactor
   mainly ATP d. energy carrier
   enters a reaction e. product
   catalytic protein


10. Cellular respiration is completed in the __.
    a. nucleus c. plasma membrane
    b. mitochondrion d. cytoplasm


11. Match each type of metabolic reaction with its function.
    glycolysis a. many ATP, NADH,
    Krebs cycle FADH 2 , and CO 2 form
    electron transport b. glucose to two
    pyruvate molecules
    and some ATP
    c. H^1 flows through
    channel proteins, ATP
    forms


12. In a mitochondrion, where are the electron transport
    systems and enzymes required for ATP formation located?

CritiCaL thinKing

1. Using Section 3.3 as a reference, suppose you want
   to observe the surface of a microscopic section of bone.
   Would the best choice for this task be a compound light
   microscope or an electron microscope?


2. Jogging is considered aerobic exercise because the cardio-
   vascular system (heart and blood vessels) can adjust to
   supply the oxygen needs of working cells. In contrast,
   sprinting the 100-meter dash might be called “anaerobic”
   (lacking oxygen) exercise, and golf “non aerobic” exercise.
   Explain these last two observations.


3. Section 3.17 mentions that arsenic poisons human cells
   because it halts the production of ATP. This happens
   because the structure of arsenic atoms closely resembles
   that of phosphorus atoms—so close, in fact, that arsenic can
   take the place of phosphorus in chemical reactions. Why
   would the substitution of arsenic atoms for phosphorus
   atoms prevent the formation of ATP?


4. The cells of your body never use nucleic acids as an energy
   source. Can you suggest a reason why?

Nanoparticles are bits of nonliving matter

thousands of times smaller than a typical

cell. Some types glow when they are

exposed to light. Now researchers are

inserting them into living cells, where they

can literally shine light on how proteins and

perhaps other kinds of molecules interact

as life processes take place.

your Future

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