The viable plate count is the most commonly used method to estimate the number of viable cells in a sample; while the Petroff-Hausser counting chamber is a direct microscopic count method generally used for counting bacteria and sperm cells.
The Petroff-Hausser counter is a counting chamber used to count microorganisms and cells (e.g., bacteria and spermatic cells) under the microscope.
The Petroff-Hausser counter chamber is divided into 25 large squares which are in turn divided by double lines. Moreover, within each large square, there also are 16 small squares divided by single lines.
Petroff-Hausser counting chambers are often used to directly determine the number of bacteria in a culture or liquid medium. Petroff-Hausser counting chambers are used to count the number of cells in a given volume of culture liquid by observing 10 to 20 microscope fields.
The viable plate count, also known as simply plate count, is the most commonly used procedure to estimate the number of viable cells in a sample.
The viable plate count method consists in obtaining serial dilutions of a sample having viable microorganisms/cells which are plated onto a growth medium.
This method (viable plate count) can be used to determine the number of actively dividing cells.
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Why should body temperature not be allowed to fluctuate too much?
Answer:
Because that can destroy the helpful enzymes in the body, and therefore cause a lot of problems or maybe cause death
some strains of __________________ produce proteins that kills certain insects such as lepidopterans , coleopterans and dipterans
Answer:
Bacillus thuringiensis
Explanation:
some strains of Bacillus thuringiensis produce proteins that kills certain insects such as lepidopterans , coleopterans and dipterans
Answer:
Bacillus thuringiensis
In New York, the worst-hit state, a total of 350,121 cases have been confirmed and 28,232 deaths have been reported. There are now 29 states with tens of thousands of cases, and more than 50,000 in New York, New Jersey, Massachusetts, Illinois, California, Pennsylvania and Michigan
Answer:
Thats true
Explanation:
List 3 variable that Anurag should keep the same
Answer:
seawater ,upside-down funnel and seaweed
Explanation:
What is the fallopian tube fimbriae made of? Pls I need help asap
Answer:
The mucous membrane would be the answer
The two most important environmental factors affecting animals are __________ and __________. edtell
Explanation:
The two most important environmental factors affecting animals are biotic and abiotic.
Hope it helps you! ＼(^ᴥ^)／
The two most important environmental factors affecting animals are biotic and abiotic.
What is the Environment?The environment may be defined as anything which is present in the surrounding of a living organism. The term environment was given by Carlyle.
Biotic factors include producers which are autotrophic in nature. Herbivores, Carnivores, omnivores, decomposers, parasites, etc.
Abiotic factors are generally long-lasting environmental conditions such as temperature, light, rain, fire, winds, etc., and topographic factors like mountains, hills, plains, desert, etc.
Therefore, the two most important environmental factors affecting animals are biotic and abiotic.
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What component of Earth's atmosphere exists entirely as a result of photosynthesis?
oxygen pas
n mas
O water vapor
O nitrogen gas
O carbon dioxide gas
Answer:
Explanation:
Carbon dioxide
For every 100ml of deoxygenated blood delivers approximately _____ml of CO2 to the alveoli.
Answer:
For every 100ml of deoxygenated blood delivers approximately __4___ml of CO2 to the alveoli.
Answer:
4ml
Explanation:
For every 100ml of deoxygenated blood delivers approximately 4 ml of CO2 to the alveoli.
Hope it is helpful....how do cells of plant devide without centrioles? explain
Answer:
Because the spindle fibers originate outside the nuclear membrane, plant cells can divide without centrioles.
~OAmalOHopeO
Leaves stalks flowers roots fruits and seeds are plant
Answer:
I'm confused as to what it is you are asking like are you asking or telling because I cant tell
Explanation:
identify the following organism and state to which phylum it belongs
Answer:
it belongs to Coelenterata phylum.
What happens during rusting of an iron nail?
1 sulfur and oxygen combine to form a sulfur dioxide coating
2 iron and oxygen combine to form iron oxide
3 sulfur, iron, and oxygen combine to form iron sulfoxide
4 iron and sulfur combine to form iron sulfide
Answer: the correct answer is B number 2
Explanation: I just answered this question
Two species have homologous structures. What do these homologous structures show about the evolutionary relationship between the two species?
Phân tích các quy luật hoạt động thần kinh cấp cao ở trẻ và vận dụng trong thiết lập thói quen học tập và kỉ luật ở học sinh tiểu học.
Answer:
very different than ducks do u want it is not the
what kind of mutation occurred when the DNA strand changed from AATCGTCCG TO AATAGTCCG?
Answer:
Missense Mutation
Explanation:
AAT CGT CCG to AAT AGT CCG where CGT has become AGT is a point mutation. If a point mutation changes the amino acid, it’s called a missense mutation. In this case CGT (arginine) has become AGT (serine).
What variable should Anurag change in his experiment
Answer:
For geological carbon sequestration, the reaction of aqueous CO2 with silicate rock permits carbonate formation, achieving permanent carbon sequestration.A
Explanation:
The meaning of ALARA in radiation?
Answer:
The guiding principle of radiation safety is “ALARA”. ALARA stands for “as low as reasonably achievable”.
A large section of tropical rainforest is cleared to build roads for mining. Select the least likely outcome of this habitat fragmentation from the options below. a.) Species that require open grazing areas may not survive. b.) Species will quickly adapt and re-populate the area. c.) The environment on the habitat edges will support different plants and animals. d.) Subpopulations of species may emerge.
Answer:
B
Explanation:
B - Species, especially ones with small niches, that looses their niches will likely die out or move to another location. Roads Will, in general, also disrupt the ecosystem (or the remains of it) and its inhabitants, which might lead to migration once again. That would be my reasoning at least. (:
Given the enormous heterogeneity of antigen receptors expressed on the populations of naive B and T lymphocytes, the adaptive immune response relies on a process whereby the rare lymphocyte that binds to the antigen is first induced to proliferate, before it can perform its effector function. For B cells, there is a clever mechanism that ensures that the specificity of the antibody secreted by the plasma cell will recognize the same pathogen that initially stimulated the B cell antigen receptor and induced B cell proliferation. This mechanism is:
Answer:
The naïve B cell expresses a membrane-bound form of the antibody as a receptor and secretes that same antibody when it differentiates into a plasma cell.
Explanation:
Naive B cell is a type of B cell that has still not been exposed to the antigen. The B cell receptors (BCRs) are transmembrane proteins composed of 1-a surface immunoglobulin molecule capable of recognizing the antigen, and 2-two transmembrane subunits that transduce the signal. When a B cell binds to antigen with its BCR, the B cell will proliferate and differentiate into a plasma cell. This plasma cell then releases antibodies, which are soluble forms of the BCR where the transmembrane domain that anchors the antibody protein to the membrane of the B cell is eliminated.
What is the fubtion of the nerves
Answer:
carry messages to and from the brain and spinal cord and the rest of the body
OR
it is a bundle of fibers that receives and sends message between the body and the brain
Answer:
The nervous system is the body's primary governing, regulating, and communication system. It is the hub of all mental activity, such as thinking, learning, and remembering. The nervous system, together with the endocrine system, is in charge of regulating and maintaining homeostasis.
OAmalOHopeO
Cystathioninuria can be caused by two different mutations in the enzyme cystathionase. Cystathioninuria caused by mutation 1 can be overcome by providing cells with increasing concentrations of the coenzyme pyridoxal phosphate. Which of the following statements describe the most likely changes in the binding affinities of the two mutant enzymes?
A. Both mutant enzymes have lost the ability to bind the substrates.
B. The enzyme with mutation 1 has lost the ability to bind to the substrates, whereas the enzyme with mutation 2 has lost the ability to bind to pyridoxal phosphate.
C. The enzyme with mutation 1 has decreased affinity for pyridoxal phosphate, whereas the enzyme with mutation 2 has lost the ability to bind to the substrates.
D. Both mutant enzymes have lost the ability to bind pyridoxal phosphate.
Answer:
C. The enzyme with mutation 1 has decreased affinity for pyridoxal phosphate, whereas the enzyme with mutation 2 has lost the ability to bind to the substrates.
Explanation:
A coenzyme is an organic cofactor that binds with an enzyme in order to initiate or aid the function of the enzyme. A coenzyme binds to the active site of the enzyme (where the reaction occurs), thereby triggering its activation by modifying protein structure during the reaction. Some examples of coenzymes include Coenzyme A and Adenosine triphosphate (ATP). Pyridoxal phosphate is a coenzyme (it is the active form of vitamin B6) that is required for the function of cystathionase. Moreover, cystathionase is an enzyme that enables cells the synthesis of cysteine from methionine (transsulfuration pathway). The binding of pyridoxal phosphate to the enzyme increases the binding affinity of the enzyme for the substrate, thereby influencing its activity. In this case, it is expected that mutation 1 reduces the binding affinity of the enzyme to the cofactor, and thereby the cofactor is required at a higher concentration to restore normal enzyme activity.
What do MSDS sheets do, in your own words
Answer: The MSDS lists the hazardous ingredients of a product, its physical and chemical characteristics (e.g. flammability, explosive properties), its effect on human health, the chemicals with which it can adversely react, handling precautions, the types of measures that can be used to control exposure
Explanation:
What is a function of the integumentary system?
1 forms blood clots
2 grows new tissue
3 absorbs water
4 break down chemical bonds in food
Answer:
absorbs water is a function of the integumentary system. hope it help you.
A function of the integumentary system is to grow new tissues. Thus, the correct option B.
What is the Integumentary system?The integumentary system may be defined as a unique type of system that primarily consists of the skin, hair, nails, and exocrine glands. It is the set of organs that construct an outermost layer of an animal or human body.
The integumentary system plays a significant role in the growth of new tissues within the body. The cells of the skin generally hold the mechanism of renewal or replacement of injured or damaged cells which are present on the epidermis part of a specific organ.
The integumentary system also protects the body from infections, and injuries provide defense against pathogens, etc.
Therefore, a function of the integumentary system is to grow new tissues. Thus, the correct option B.
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which life cycle stage is found in plants but not animals
Answer:
Multicellular haploidOAmalOHopeO
Plants have multicellular haploid and multicellular diploid stages in their life cycle.
Gametes develop in the multicellular haploid gametophyte . Fertilization gives rise to a multicellular diploid sporophyte, which produces haploid spores via meiosis.What is multicellular haploid stage?The haploid multicellular stage produces specialized haploid cells by mitosis that fuse to form a diploid zygote.The zygote undergoes meiosis to produce haploid spores. Each spore gives rise to a multicellular haploid organism by mitosis.To know more about diploid stage here
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Cells control or regulate the flux through metabolic pathways by means of I. allosteric control of enzymes. II. covalent modification of enzymes. III. genetic control of the concentrations of enzymes. IV. genetic expression of allosteric regulators.
Answer:
I, II, III
Explanation:
Allosteric regulation is a common mechanism of regulation of enzyme activity, which generally involves key enzymes in metabolic pathways. Allosteric modulation occurs when a substance/molecule called 'allosteric regulator' binds to an enzyme at a site other than the enzyme's active site, thereby triggering a conformational change in the enzyme and thus affecting its activity. Moreover, covalent modifications such as phosphorylation, acetylation, methylation, etc, are also involved in the regulation of enzymatic activity in metabolic pathways. For example, phosphorylation is a type of reversible covalent modification of proteins consisting of the addition of phosphate groups at specific amino acid residues (i.e., serine, threonine, and tyrosine) by specific enzymes known as protein kinases. Phosphorylation alters the three-dimensional (3D) structure of proteins, thereby turning the substrate or cellular pathway to active and/or inactive. Finally, both transcriptional and post-transcriptional mechanisms are also able to control the expression of enzymes involved in signaling pathways. Transcriptional mechanisms are capable of limiting the amount of mRNA that is produced from a given gene (in this case, an enzyme encoding gene), whereas post-transcriptional mechanisms such as, for example, RNA interference pathways, control the translation of messenger RNA (mRNA) molecules into proteins.
Compared with a eukaryotic cell, a prokaryotic cell Select one:______
a. lacks organelles beyond ribosomes.
b. is larger.
c. does not require energy.
d. is not living.
e. has no method of movement.
What will the percentage of cytosine be in this segment of DNA?
Answer:
15%
Together, adenine and thymine compose 70% of the segment. This means that 30% of the section is composed of guanine-cytosine pairs. Since these two bases will be equal in quantity, 15% of the DNA section will be cytosine bases.
What is the function of the mitochondria?
A. Stores the cell's DNA
B. Builds proteins
C. Produces energy for the cell by respiration
OD. Stores the cell's glucose
Reset Selection
Answer:
Produces energy for the cell by respiration
Explanation:
The glucose obtained from food is broken down to pyruvic acid in the cytoplasm. This pyruvic acid is broken down into oxygen, water and energy rich ATP molecules in the Mitochondria.
Fertilization, Fruit and Seed Formation x3 3. a. name the two processes that lead to seed formation in flowering
Answer:
Pollination, the transfer of pollen from flower-to-flower in angiosperms or cone ... In angiosperms, the process of seed development begins with double ...
Missing: x3 | Must include: x3
Ecosystems rely on interdependence between species to keep balance. Which of the following is a threat to a stable
ecosystem?
A. Loss of biodiversity
B. High biodiversity
C. Low biodiversity
D. Increase in biodiversity
Answer:
loss of biodiversity
Explanation:
Biodiversity- refers to the variety of life on Earth at all its levels, from genes to ecosystems, and can encompass the evolutionary, ecological, and cultural processes that sustain life.
loss in biodiversity affect food chains greatly
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