Download Unit 1 Review

Understanding Concepts
1. (a) Cells are the basic structural and functional units of life.
(b) All cells arise from the division of other cells.
(c) All living things are composed of one or more cells.
2. (a)
Type of microscope Magnifying Maximum Maximum
energy source magnification resolution
scanning electron microscope electrons 300 000X 10 nm
compound light microscope light 2000X 200 nm
transmission electron microscopes electrons 5 000 000X 0.2 nm
(b) total magnification
(15 )
(100 )
total magnification
1500
NEL Unit
1 Review 33
cell
membrane
cell wall
nucleus
7.5 :m
Figure 1
3.
Diagram of Plant/animal/
Cell component cell component both Main function
nucleus both control of cellular activities
cell membrane both controls movement of
substances into and out
of cells
cell wall plants cell rigidity
4.
34 Unit 1 Student Book Solutions NEL
nucleus
lysosome
Animal Cell
(macrophage)
lysosome
(contains
digestive
enzymes)
phagosome
pseudopods
pseudopods
surround
bacterial cell
pseudopods
fuse to form
food vacuole
(phagosome)
lysosome
fuses with
phagosome
and releases
digestive
enzymes into
phagosome Bacterial cell is digested
by digestive enzymes into
nutrient molecules.
Molecules are absorbed
into macrophage’s
cytoplasm through
phagosome membrane.
5. Student solutions will vary. Important points to include in the résumé include:
• small, quickly dividing heterotroph with very small energy needs
• eats inexpensive carbohydrates like sucrose and glucose
• produce large amounts of carbon dioxide gas, which will makes baked goods soft and fluffy
6. Similarities: 1. Chloroplasts and mitochondria are either circular or oval organelles of roughly similar size. 2. Both
organelles contain inner and outer membranes.
Differences: 1. The inner membrane of a mitochondrion in folded into cristae, while the innermost membrane of a
chloroplast is fashioned into many stacked chambers called thylakoids. 2. The inner membrane of mitochondria
contains enzymes used in cellular respiration. The thylakoid membranes of a chloroplast contain chlorophyll
molecules
that begin the process of photosynthesis.
7. (a) Amyloplasts store starch. Chromoplasts store coloured pigment molecules.
(b) amyloplast— Figure 1
chromoplast— Figures 2 and 3
8. (a) Sperm cells contain lots of mitochondria; most fat cells contain few mitochondria.
(b) Sperm cells move by wiggling flagella. Thus, they need lots of mitochondria to produce energy for their flagella.
Fat cells do not move, so they do not need large amounts of energy.
9. Chlorophyll molecules are embedded in thylakoid membranes in chloroplasts.
10. (a) A different set of genes are active in skin cells than in nerve cells.
(b) Stem cells are not specialized like skin cells and nerve cells. Stem cells have the potential to become almost any
type of specialized cell.
11. An oxygen atom is composed of a single atom, but an oxygen molecule contains two oxygen atoms attached by a
double covalent bond.
12. hydrogen bond, ionic bond, covalent bond
13. (a) H 2 S and HBr are polar.
(b) CH 4 is hydrophobic; H 2S and HBr are hydrophilic.
14. (a) W ater dissolves more solutes than any other solvent.
(b) Polar solvents dissolve polar (and ionic) solutes; nonpolar solvents dissolve nonpolar solutes. Oil (nonpolar) does
not dissolve in water (polar); alcohol (polar) dissolves in water (polar).
15. (a) An acid-base buffer is a solution that may neutralize small amounts of acids and bases.
(b) Acid-base buffers contain approximately equal concentrations of an acid and a base.
(c) The carbonic acid–bicarbonate buffer exists in the human body. The carbonic acid component neutralizes small
amounts of base that enter the body and bicarbonate ions neutralize small amounts of acid.
16. Plant cells use cellulose to build cell walls. Humans use cellulose to prevent constipation.
17. (a) Fatty acids in triglycerides of oils are unsaturated or polyunsaturated. The fatty acids in triglycerides of butter
are
saturated.
(b) Fatty acids of vegetable oils are hydrogenated to convert them to margarine.
(c) Steroids and fatty acids are hydrophobic. Steroids are ring molecules; fatty acids are linear molecules.
18. Plants use waxes as waterproof coatings; animals like bees use waxes to build honeycombs.
19. (a) protein
(b) amino group, carboxyl group
20. All of them— horse hoofs, spider webs, and egg whites— are composed of proteins.
21. (a) The identity of a protein depends on the number and the sequence of amino acids in its structure. W ith 20
different
amino acids to choose from, a polypeptide 200 amino acids long can take 200 20 different configurations, each
forming a different protein with a different function.
(b) The sequence of nucleotides in DNA determines the sequence of amino acids in proteins.
22. (a) The three-dimensional shape of a protein creates crevices that act as active sites where substrates attach.
(b) They become denatured. This is dangerous because denatured enzymes lose activity, and cannot catalyze
reactions
effectively.
(c) Cooking denatures the proteins in a steak, and makes the steak easier to chew.
23. (a) DNA stores genetic information. RNA takes the genetic information from the nucleus to the ribosomes in the
cytoplasm where it is used to produce proteins.
(b) Messenger RNA; it transports the genetic information in DNA from the nucleus to the ribosomes in the
cytoplasm.
24. (a) ATP transfers energy to energy requiring reactions in a cell.
(b) It will die.
25. In the induced fit model, the enzyme changes its shape to accommodate a binding substrate. After reaction, the
shape
of the enzyme changes again to release the products of the reaction. The induced-fit model is illustrated in Figure 3,
on page 52 of the Student Text.
NEL Unit
1 Review 35
26. (a) A simple diffusion
B facilitated diffusion
C active transport
(b) The purple blob represents a transmembrane carrier protein.
(c) M ethod C uses ATP, and may transport solutes against a concentration gradient.
27. (a) Simple diffusion ends when the solute concentration is uniform throughout
(b) When solute concentration is uniform, particles move in all directions at the same rate.
(c) No; Active transport uses energy to pump solute particles against a concentration gradient, and may cause all
particles to go one way.
28. Transmembrane protein carriers of active transport require the use of ATP to move solutes across a selectively
permeable
membrane. Facilitated diffusion carriers don’t use ATP.
29. (a) A is hypotonic, B is isotonic, C is hypertonic
(b) They will burst because water will continue to enter the cells by osmosis.
(c) Cells C may eventually shrivel up and die of dehydration (lack of water in their cytoplasm).
30. (a)
(b) Pinocytosis brings large quantities of extracellular fluid into a cell by infoldings of the cell membrane. Cellular
energy is used in pinocytosis. Simple diffusion is the movement of solutes, through a selectively permeable
membrane, into or out of a cell, down a concentration gradient. Cellular energy is not used in simple diffusion.
31. It enters a mitochondrion and is processed through the reactions of oxidative respiration.
32. (a) glycolysis
(b) 2 ATP molecules
33. Lactate fermentation occurs in human muscle cells during strenuous exercise.
34. (a) During strenuous exercise, cells do not receive enough oxygen to carry out aerobic cellular respiration.
Instead,
cells undergo lactic acid fermentation, producing lactic acid as a final product. W hen the person stops exercising,
lactic acid is converted back into pyruvic acid, and additional oxygen must be breathed in to process the pyruvic
acid through the reactions of oxidative respiration. The additional oxygen required is referred to as an oxygen debt.
(b) The person “pays” the oxygen debt by panting after a bout of strenuous exercise.
36 Unit 1 Student Book Solutions NEL
animal cell sends
out pseudopods that
surround a small
portion of extracellular
fluid
pinocytotic
vesicle
pseudopods fuse
and form a
pinocytotic vesicle
containing
extracellular fluid
pseudopods
animal
cell
Applying Inquiry Skills