CHAPTER FOUR- CELLS

Question 1

Cell theory

Answer 1

All living organisms are made up of one or more cells & all cells arise from other preexisting cells

Question 2

What does a cell need to be alive

Answer 2

(1) Plasma membrane to keep outside out and inside in (2) DNA as hereditary information that encodes proteins (3) all cells make proteins using ribosomes (4) ability to transform energy from one form to another

Question 3

Prokaryotes

Answer 3

(1) Bacteria and archaea (2) small size (3) no intracellular organelles (4) enclosed in cell wall made of Peptidoglycan (PG) (5) Circular DNA (6) ribosomes smaller and less dense (6) Divide by binary fission

Question 4

Eukaryotes

Answer 4

(1) protests, fungi, plants, animals (2) larger size (3) possess intracellular organelles (4) if they have cell walls there is no PG (5) linear DNA (6) Ribosomes are larger and denser (7) divide by mitosis or meiosis

Question 5

Typical Eukaryotic cell features

Answer 5

(1) DNA contained in nucleus (2) cytoplasm contains specialized structures called organelles (3) larger than prokaryotes

Question 6

Four structures in all prokaryotes

Answer 6

(1) Plasma membrane: encloses cell contents: DNA, ribosomes and cytoplasm (2) Cytoplasm: jelly like fluid inside the cell (3) DNA :one or more circular loops containing genetic information (4) Ribosomes: granular bodies in the cytoplasm that convert genetic information into protein structures

Question 7

Typical Prokaryotic cell features

Answer 7

(1) No nucleus- DNA is in cytoplasm (2) Internal structure mostly not organized into compartments (3) Much smaller than eukaryotes

Question 8

Endosymbiosis - explains presence of mitochondria and chloroplasts in eukaryotes

Answer 8

(1) ancestral eukaryote engulfs prokaryote (2) ancestral eukaryote and prokaryote merge (3) over time, the engulfed prokaryote evolves into an organelle such as mitochondria

Question 9

Invagination

Answer 9

(1) plasma membrane folds in on itself (2) inner compartments (organelles) are formed

Question 10

Plasma Membrane

Answer 10

made up of two layers that are filled with a variety of pores, molecules and channels

Question 11

Plasma Membrane functions

Answer 11

(1) Holds contents of cell in place (2) takes in food and nutrients (3) aids in building and exporting molecules (4) allows interactions with the environment and neighboring cells

Question 12

Evidence for Endosymbiosis

Answer 12

(1) Mitochondria (M) and Chloroplasts (C) are same size as bacteria (2) M &C have circular DNA like prokaryotes (3) M&C divide by binary fusion (4) Ribosomes present in M&C are similar to bacterial ribosomes

Question 13

Diffusion

Answer 13

(1) A solute is dropped into a solvent (2) Solute molecules move about randomly bumping into each other (3) random motion of molecules causes them to end up evenly distributed

Question 14

Passive transport

Answer 14

occurs when molecules move across a membrane without energy input– molecules move down their concentration gradient

Question 15

Simple diffusion

Answer 15

molecules pass directly through the plasma membrane without assistance of anther molecule

Question 16

Facilitated diffusion

Answer 16

Molecules move across the plasma membrane with the help of a channel or carrier molecule

Question 17

Osmosis

Answer 17

Movement of water across a selectively permeable membrane from an area of high water concentration to an area of low water concentration

Question 18

Isotonic solution

Answer 18

solute concentration is balanced– water movement is balanced

Question 19

Hypotonic solution

Answer 19

solute concentrations lower outside the cell– water goes into cell

Question 20

Hypertonic solution

Answer 20

solute concentration higher outside cell – water diffused out of cell