1. You are given a 1 gram soil sample of unknown bacterial load. After doing 10-fold serial dilutions of the soil in sterile water, 100 uL volumes are taken from each dilution for preparation of pour plates. Following incubation, each half of the 10-8 plate has 46 colonies.
a) What was the dilution factor?
b) How many bacteria were present in the soil?
2. Staphylococcus aureus divides every 20 minutes. A culture begins with 10 bacterial cells.
a) After 5 hours, how many generations have occurred
b) After 5 hours, how many bacteria are present?
3. How many milliliters would you need to prepare a 10-2 dilution from a 10ml starting culture?
Answers
Answer:
1a. 1:10
1b. 4.6×10¹³
2a. 15generations
2b. 327,680
Explanation:
10 fold serial dilution means 1ml of stock is mixed in 9ml distilled water. This is called as 10⁻¹ solution.
In this way, take 1ml each of every dilution and mix in 9ml distilled water to make 10⁻², 10⁻²-------10⁻⁸ dilutions.
Now, CFU/ml = no. of colonies × dilution factor/ volume of sample plated.
Related Questions
DNA damage checkpoints are crucial for preventing cell proliferation when DNA damage has occurred. The role of DNA checkpoint proteins in the cell cycle is closely tied to the roles of DNA repair enzymes, although these proteins perform different functions.1. Which of the following statements is true for DNA checkpoint proteins and not for DNA repair enzymes? a. These proteins remove a single nucleotide of damaged DNA. b. These proteins nick the phosphodiester backbone of the damaged DNA. c. These proteins prevent the cell cycle from progressing if damaged DNA is detected. d. These proteins remove the region of damaged DNA. 2. Which cell cycle phases contain critical DNA damage checkpoints?a. Gob. G1c. G2d. M
Answers
Answer:
1. C. These proteins prevent the cell cycle from progressing if damaged DNA is detected.
2. C. G2
Explanation:
1. All other choices apply uniquely to DNA repair enzymes (i.e. not to DNA checkpoint proteins).
2. Go doesn't contain any critical DNA damage checkpts. because it's not even an official part of the cell cycle; it's simply a phase in which cells are arrested. G1 doesn't contain any critical DNA damage checkpts. because it's before DNA is replicated. G2 is right after S phase when the DNA is replicated; thus, it contains critical DNA damage checkpts.
Question 21 (5 points)
Which of the following terms describes a collection of hollow cells that implants on
the uterus wall after fertilization, but is not yet differentiated (in other words, all cells
are the same type of cell still)?
Fetus
Haploid
Mitosis
Blastocyst
Answers
Answer:
The answer is option D.
Blastocyst
Hope this helps
Answer:
Blastocyst
Explanation:
Once an egg is fertilized by a sperm, it begins to divide by mitosis into a 2, 4, and then 8 celled structure. Eventually, this large collection of cells keeps dividing and becomes a hallow collection of undifferentiated cells called a blastocyst. The blastocyst will implant on the wall of the uterus where it will begin to grow and develop during pregnancy into a fetus.
What are gyres?
1.Large plants that move in circles in the ocean.
2.Large circulating parts of the ocean
3.Large animals in the ocean that move in circles in the ocean.
Answers
Answer:
A gyre is a circular ocean current formed by the Earth's wind patterns and the forces created by the rotation of the planet..
Explanation:
follow me plzzz
Mendel first crossed true-breeding plants to produce a second generation, which were then allowed to self-pollinate to generate the offspring. How do we name these three generations?
Answers
Answer:
P, F1 and F2
Explanation:
The first generation crossed which included the true breeding parents are the P generation plant. This produces the two subsequent generations which are the first filial generation (F1) and the second filial generation (F2).
A biologist is studying how green sea turtles choose where to lay their eggs. She makes a hypothesis that because this species is related to other sea turtles through common ancestry, they probably all use the same process. This biologist formed her hypothesis using:________
a. A hunch
b. The unifying theory of evolution
c. Experimentation
d. The scientific method
e. Observations of green sea turtles' behavior
Answers
Answer:
Option b
Explanation:
Hypotheses are carried out as proposed explanation made on the basis of limited evidence which serves as a beginning point for further study.
The biologist in this case has a limited evidence with regards to this species which is just only about its ancestry, so her hypothesis was based on the unifying theory of evolution which is the framework within which biologists ask questions about the living world providing predictions with regards to directions about living things.
The correct answer, unequivocally, is (B).
- This is because she used her knowledge that, from an standpoint of evolution, these turtles were related to each other.
Which statement best describes monsoons?
They force cool, moist air from oceans to rise.
They are winds that blow in the opposite direction of a normal wind.
They bring heavy rain in the winter and in the summer.
They influence precipitation as wind moves near a mountain.
Answers
Answer:
The correct answer to the following question will be Option B and C.
Explanation:
Monsoon seems to be a change throughout the course including its predominant hot air flowing from either the south-western oceans of India towards India.The summer monsoon gives a luxurious atmosphere as well as heavy rains to something like the coastline of Asia (south-east), where many monsoon showers of rain undergo their rainy season throughout the winter.The other choices are not related to the given circumstances. So that Option B & C would be the appropriate choice.
Answer:
Pretty sure its B not sure tho. If its correct, mark as brainliest
Explanation:
what is cellular affinity in biology?
Answers
Answer:
affinity. Attraction between particles. Biology: A measure of the attraction of one biological molecule toward another molecule, either to modify it, destroy it, or form a compound with it. Examples are enzymes and their substrates, or antibodies and their antigens.
What should be done following health violations from an inspection?
Answers
Answer:
correct the identified
Explanation:
If health violations are found out during inspections, the inspector should give him warning about the violation or give him a ticket or fine. If high level of violation if found out, then the license of the restaurant or company should be cancelled.
What is heath violation?Health violation is avoiding the condition that are necessary for health during the process or manufacturing. These violation leads to the poor health of the people.
Health inspectors are the person who check the conditions of hotel and factories related to the health of the people. If they found any violation, the companies should correct them.
Thus, the inspector should issue him a warning about the infringement or issue him a ticket or fee if any health violations are discovered during inspections. If a serious breach is discovered, the restaurant's or business' license should be revoked.
To learn more about heath violation, refer to the link:
https://brainly.com/question/14714594
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Antimicrobial peptides can do all of the following except:_________A) regulate body temperature.B) target intracellular components.C) insert themselves into target cell membranes.D) disrupt plasma membrane and/or cell wall.E) stimulate leukocytes.
Answers
Answer:
Option A
Explanation:
Antimicrobial peptides cannot regulate body temperature. They can do all of the rest.
=> target intra cellular components.
=> insert themselves into target cell membranes.
=> disrupt plasma membrane and/or cell wall.
=> stimulate leukocytes.
Which statement summarizes a change that occurs during photosynthesis?
Answers
Answer:
It converts light energy to chemical energy.
Explanation:
Its absorbing sunlight and changing in to chemical energy for the plants nutrients.
During photosynthesis, light energy will be changed into chemical energy.
What is photosynthesis?Photosynthesis was a process used mostly by plants as well as other creatures to transform sunlight into chemical energy which, via cellular respiration, might subsequently be produced to fuel the organism's functions.
What is chemical energy?Chemical energy was the energy that would be generated while chemical substances engage in a chemical reaction but also change into some other substances.
Therefore, during photosynthesis, light energy will be changed into chemical energy.
To know more about photosynthesis and chemical energy.
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Researchers cross a corn plant that is pure-breeding for the dominant traits colored aleurone (C1), full kernel (Sh), and waxy endosperm (Wx) to a pure-breeding plant wiht the reccessive trains colorless aleurone (c1), shrunken kernal (sh), and starchy (wx). The resulting F1 plants were crossed to pure-breeding colorless, shrunken, starchy plants. Counting the kernals from about 30 eats of corn yields the following data:
Kernel Phenotype Number
Colored, shrunken, starchy 116
Colored, full, starchy 601
Colored, full, waxy 2538
Colored, shrunken, waxy 4
Colorless, shrunken, starchy 2708
Colorless, full, starchy 2
Colorless, full, waxy 113
Colorless, shrunken, waxy 626
6708
A) Why are these data consistent with genetic linkage among the three genes?
B) Perform a chi-square test to determine if these data show significant deviation from the expected phenotype distribution.
C) What is the order of these genes in corn?
D) calculate the recombination fraction between the gene pairs.
E) what is the interference value for this data set?
Answers
D) #recombinant=116+601+4+2+113+625=1462
#nonrecombinant=2538+2708=5246
RF=R/(N+R)=1462/6708=0.2
E) I=1-Q
I-interference
Q-coefficient of coincidence
Q=O2Xo/E2xo(2xo-double crossovers)
O2xo=6
P=(distance from C1 to Sh/100)*(distance from Sh to Wx/100)
=(3.38/100)*(18.28/100)=0.006
E2xo=0.006*6708=40.248
Q=6/40.248=0.15
I=1-0.15=0.85