Lab 1: Factors Affecting Microbial Growth

Question 1

what do bacteria need to grow?

Answer 1

-H2O
-C
-Energy
-Nitrogen
-Minerals
-Growth Factors

Question 2

describe growth factors

Answer 2

-organic molecules
-organisms can NOT make them on their own
-for growth or enzymatic reactions

Question 3

define photoautotrophs

Answer 3

use CO2 as their C source and solar energy to make ATP

Question 4

define chemoautotrophs

Answer 4

carbohydrates, proteins, lipids are used as C source and to make ATP

Question 5

most bacteria are

Answer 5

chemoheterotrophs

Question 6

bacteria are…

Answer 6

ubiquitous

Question 7

how do you sterilize culture media?

Answer 7

by autoclaving

Question 8

what is the temperature and pressure that autoclaves operates at?

Answer 8

121 degrees Celsius
15 psi

Question 9

types of culture media

Answer 9

-broth
-plate
-slant

Question 10

agar is…

Answer 10

a polysaccharide extracted from algae used to thicken culture media

Question 11

list the 5 types of agar plates and broths

Answer 11

1. chemically defined
2. complex
3. enrichment
4. selective
5. differential

Question 12

what types of agar plates and broths will be used in this lab?

Answer 12

complex

Question 13

describe a chemical culture media

Answer 13

-exact chemical composition known
-minimal amount of nutrients needed for survival
-synthetic

Question 14

describe a complex culture media…

Answer 14

-exact composition is NOT known
-made from meat and soybean extract

Question 15

describe a enrichment culture media…

Answer 15

-has extra growth factors to support the organisms with special nutritional needs

Question 16

give an example of an extra growth factor that can be added to a TSA plate

Answer 16

sheep’s blood

Question 17

describe a selective culture media…

Answer 17

-has special chemicals that stimulate growth of some bacteria while inhibiting the growth of others

Question 18

give an example of selective medium that can be added to a TSA plate

Answer 18

adding an antibiotic that allows only resistant bacteria to grow

Question 19

describe a differential culture media…

Answer 19

-has pH indicators; allows for different organisms to be distinguished by changing color

Question 20

what are the 3 different classifications of bacteria?

Answer 20

1. morphological
2. cultural
3. physiological

Question 21

define morphological characteristics

Answer 21

shape of individual bacteria cells, arrangement, and size
-require a microscope to be viewed

Question 22

define cultural characteristics

Answer 22

form, color. and size of colonies on plates and the pattern of growth in broths

Question 23

define physiological characteristics

Answer 23

biochemical (metabolic) reactions carried out by the organism
-requires both selective and differential media

Question 24

define hemolysis

Answer 24

an enzyme secreted by some bacteria that breaks open RBCs

Question 25

hemolysis is observed on a ____ and has a ___ __ ____ around the colonies

Answer 25

BAP
zone of clearing

Question 26

when you can observe and classify the appearance of bacterial colonies, you are observing _______ characteristics.

Answer 26

cultural