Download 1.16 Answers

SECTION 1.16 QUESTIONS
(Page 71)
Understanding Concepts
1. (a) Similarity: Active transport and facilitated diffusion use transmembrane protein carriers to move materials
across
a selectively permeable membrane.
Differences: 1. Active transport uses ATP; facilitated diffusion does not. 2. Facilitated diffusion carries solutes
down a concentration gradient; active transport may carry substances against a concentration gradient.
(b) sodium ions (Na + )
2. The two types of endocytosis are phagocytosis and pinocytosis. Phagocytosis occurs when an animal cell engulfs
solid
particles in the extracellular fluid by surrounding the particles with pseudopods. The pseudopods fuse and enclose
the
particles and some extracellular fluid in a membrane sac called a food vacuole. In pinocytosis an animal cell takes in
a small portion of extracellular fluid by extending pseudopods and forming an extracellular fluid-filled pinocytotic
vesicle within the cell’s cytoplasm.
3. Endocytosis is the bulk movement of materials into a cell, from the extracellular environment, by phagocytosis or
pinocytosis. Exocytosis is the bulk movement of materials out of a cell, into the extracellular environment, by a
process
that is essentially the reverse of endocytosis. Both processes are energy consuming. In endocytosis, the cell forms
pseudopods around extracellular fluid or particles in the extracellular environment. The pseudopods fuse to form
vesicles
within the cell’s cytoplasm. In exocytosis, vesicles formed within the cytoplasm, such as those formed by the
Golgi apparatus, fuse with the cell membrane, and spill their contents into the extracellular environment.
4. (a) phagocytosis
(b) A pseudopod
B solid particle
C phagocytotic vesicle
(c) Lysosomes may fuse with a phagocytotic vesicle and digest its contents.
5. The cell membrane would decrease in size as the membrane pinched off to create phagocytotic or pinocytotic
vesicles,
without having the membrane being replaced through exocytosis.
6. hormones and enzymes
NEL Section
1.16 25
Applying Inquiry Skills
7. (a) Hypothesis: The sugar molecules are transported into the cell membrane by active transport because the
concentration
of sugar molecules move into the cell against a concentration gradient over time.
(b) This observation reinforces the student’s hypothesis because a cell would have to produce large amounts of ATP
to power the active transport process that moves sugar molecules into the cell by active transport.