Answer: 2 electrons
Explanation:
The inner shell (1st shell) can hold 2 electrons, the next shell can hold 8 electrons and the third shell can hold 18 electrons.
Answer:
2 electrons
Explanation:
Electrons have various shells. The first one is called the K shell and it holds a maximum of two electrons.The next is the L shell (8 electrons), then the M shell and so on.
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?
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.
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
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.
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.
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.
About 16% of the world's total oil output:
A) comes from offshore drilling
B) is made by the United States
C) is mined deep beyond the continental shelf
D) comes from oil rigs in the Atlantic Ocean
Answer:
The answer is A, It comes from offshore drilling.
Explanation:
Cause i got it right.
what is cellular affinity in biology?
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.