Allied Health Sciences Entry Test Biology Flashcards

24 sample cards from the Biology deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. How does temperature affect enzyme activity, including the optimum?

   Activity increases with temperature up to an optimum (often ~37 C in humans); beyond it the enzyme denatures and activity falls sharply.

2. How does substrate concentration affect the rate of an enzyme-catalyzed reaction?

   Rate increases with substrate concentration until all active sites are saturated, after which the rate levels off (maximum/plateau).

3. Why does pH affect enzyme activity, and what is meant by optimum pH?

   Extreme pH alters the charges/bonds in the active site and can denature the enzyme; optimum pH is the pH at which the enzyme works fastest (e.g., pepsin ~2, trypsin ~8).

4. What is a cofactor, and how do coenzymes and prosthetic groups differ?

   A cofactor is a non-protein helper needed for enzyme activity; a coenzyme is a loosely bound organic cofactor (often a vitamin derivative), while a prosthetic group is tightly/permanently bound.

5. Distinguish between competitive and non-competitive enzyme inhibition.

   Competitive inhibitors resemble the substrate and bind the active site (effect reduced by more substrate); non-competitive inhibitors bind a different site, change the enzyme's shape, and are not overcome by more substrate.

6. What is feedback (end-product) inhibition?

   A regulatory mechanism where the final product of a metabolic pathway inhibits an enzyme earlier in the pathway, preventing overproduction.

7. State the three principles of the cell theory.

   1) All living organisms are composed of one or more cells; 2) the cell is the basic structural and functional unit of life; 3) all cells arise from pre-existing cells.

8. What are the functions of the mitochondrion, and why is it called the 'powerhouse of the cell'?

   It carries out aerobic respiration to produce ATP (energy); it is the powerhouse because it generates most of the cell's usable energy.

9. Compare rough and smooth endoplasmic reticulum.

   Rough ER has ribosomes and synthesizes/processes proteins; smooth ER lacks ribosomes and synthesizes lipids, stores calcium, and detoxifies substances.

10. What is the main function of the Golgi apparatus?

    To modify, sort, package, and dispatch proteins and lipids into vesicles for secretion or delivery within the cell.

11. What do lysosomes contain and do?

    They contain hydrolytic (digestive) enzymes that break down worn-out organelles, food particles, and foreign material (intracellular digestion).

12. What is the function of ribosomes and what are they made of?

    Ribosomes are the sites of protein synthesis; they are composed of rRNA and proteins, with large and small subunits.

13. Describe the fluid mosaic model of the cell membrane.

    The membrane is a fluid phospholipid bilayer with proteins (and cholesterol and carbohydrates) embedded in or attached to it, able to move laterally like a mosaic.

14. Distinguish between passive and active transport across the cell membrane.

    Passive transport moves substances down a concentration gradient without energy (diffusion, osmosis, facilitated diffusion); active transport moves substances against the gradient using ATP.

15. Define osmosis.

    The net movement of water molecules from a region of higher water potential (lower solute) to lower water potential (higher solute) across a selectively permeable membrane.

16. What is the difference between endocytosis and exocytosis?

    Endocytosis brings large materials into the cell by engulfing them in a vesicle (phagocytosis/pinocytosis); exocytosis expels materials out of the cell by fusing a vesicle with the membrane.

17. List at least four differences between prokaryotic and eukaryotic cells.

    Prokaryotes: no true nucleus (nucleoid), no membrane-bound organelles, 70S ribosomes, circular DNA, usually small (1-10 um). Eukaryotes: true membrane-bound nucleus, membrane-bound organelles, 80S ribosomes, linear DNA with histones, larger (10-100 um).

18. Which organisms are prokaryotic, and which kingdoms are eukaryotic?

    Bacteria (kingdom Monera) are prokaryotic; kingdoms Protista, Fungi, Plantae, and Animalia are eukaryotic.

19. What is binomial nomenclature, who introduced it, and how is a name written?

    A two-name system introduced by Carolus Linnaeus: Genus (capitalized) + species (lowercase), italicized or underlined, e.g., Homo sapiens.

20. List the taxonomic hierarchy from the broadest to the most specific rank.

    Kingdom -> Phylum (Division in plants) -> Class -> Order -> Family -> Genus -> Species.

21. Name the five kingdoms of Whittaker's classification system and a defining feature of each.

    Monera (prokaryotic), Protista (mostly unicellular eukaryotes), Fungi (heterotrophic by absorption, chitin walls), Plantae (multicellular autotrophs, photosynthesis), Animalia (multicellular heterotrophs).

22. Who proposed the five-kingdom classification system and in what year?

    Robert H. Whittaker, in 1969.

23. To which kingdom do bacteria and cyanobacteria belong, and what cell type are they?

    Kingdom Monera; they are prokaryotic cells.

24. What mode of nutrition characterizes kingdom Fungi?

    Heterotrophic nutrition by absorption (saprophytic or parasitic), digesting food externally and absorbing the nutrients.

What this deck covers

Biology flashcards FAQ