Answer:c. DNA polymerase can join new nucleotides only to the 3′ end of a pre-existing strand.
Explanation:
The double stranded molecule of DNA having the pairing strands in the anti-parallel condition. One strand is remain in configuration as the 5’ to 3’ end, the complementary strand is positioned 3’ to 5’ end.
New DNA strand synthesis occurs from the 3’ to 5’ end as the enzyme DNA polymerase attach itself to the 3’ end of a DNA strand. It will add new nucleotides to the 3' end of the DNA.
Hence, the option (c) is the correct answer.
The primary reason for the difference in the synthesis of leading and lagging strands of DNA is that the DNA polymerase can only add new nucleotides to the 3′ ends of a pre-existing strand. DNA replication always occurs in the 5' to 3' direction, which influences the synthesis of both strands due to the anti-parallel structure of DNA.
Explanation:The basis for the difference in how the leading and lagging strands of DNA molecules are synthesized lies in the manner in which the DNA polymerase enzyme works. The key factor is that DNA polymerase can add new nucleotides only to the 3′ end of a pre-existing DNA strand.
This signifies that DNA replication always takes place in the 5′ -> 3′ direction. Considering the DNA double helix's anti-parallel structure, one strand (leading strand) is synthesized in a continuous fashion, as its orientation allows adding nucleotides at the 3′ end.
Conversely, the other strand (lagging strand) being oriented in 3′ -> 5′ direction, is synthesized discontinuously in small fragments called Okazaki fragments, as nucleotides can't be added to its 5' end. The enzyme DNA ligase then joins these pieces. Options a, b, and d may influence the process, but they're not the main reason for the leading and lagging strands' different synthesis.
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You want to test pentapeptides (short peptides with only five amino acids) for their ability to bind to and inhibit a particular receptor. To do this, you set out to synthesize all possible pentapeptides and test each individually. Assuming you’ll use just the 20 common amino acids, how many different pentapeptides will you have to test for receptor binding
Answer:
The correct answer is 3200000.
Explanation:
If there is only one amino acid in the peptide, the probable number of combinations would be 20. If there is only two amino acid in the peptide, the probable number of combinations will be 20^2. Similarly, for three amino acids in the peptide it would be 20^3 and for four it would be 20^4.
Thus, in the case of pentapeptide, that is, five amino acids in a peptide, the probable number of combinations will be 20^5, which comes out to be 3200000. Thus, the total number of different pentapeptides will be 3200000 that needs to be tested for receptor binding.
The number of different pentapeptides that will need to be tested for receptor binding is 15,504.
Explanation:In order to calculate the number of different pentapeptides that will need to be tested, we can use the formula for combinations. Since there are 20 common amino acids to choose from and we are testing for pentapeptides (peptides with five amino acids), the formula for combinations is 20C5.
Using this formula, we can calculate the number of different pentapeptides:
20C5 = 20! / (5! * (20-5)!) = 20! / (5! * 15!) = (20 * 19 * 18 * 17 * 16) / (5 * 4 * 3 * 2 * 1) = 15,504.
Therefore, there will be 15,504 different pentapeptides that will need to be tested for receptor binding.
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Light energy is converted into chemical energy in the:
a. Antenna complex
b. Reaction center
c. Stroma
d. Inner membrane
Answer:
The correct answer will be option-B.
Explanation:
Photosynthesis is the process which converts the light energy to chemical energy which is utilized in the formation of the glucose molecule.
The light-dependent reaction of photosynthesis begins when the photon of light is captured by the chlorophyll pigment molecules of the antenna complex. The chlorophyll electron gets excited which gets transferred via resonance pathway to a trans-membrane protein-pigment complex called photochemical reaction centre.
The photochemical reaction centre traps the excited electrons and passes the electron immediately to electron acceptors and an electron transport chain starts. Therefore it is the petrochemical reaction centre of the photosystem which converts light energy to chemical energy and thus, Option-B is the correct answer.
Do the Rickettsia bacteria harm or injure the tick or mite host, as we see in lice and Typhus? Explain.
Answer:
No. Rickettsia use an arthropod as a vector host to cause the disease in their final host, usually vertebrades. However, they do not harm vector host as ticks.
Explanation:
Rickettsia are strict parasites, they are bacteria that must live inside the cells of their hosts. Specifically, they are found in mammals and at some point in their life cycle, they are associated with arthropods (fleas, lice or ticks) that transport the parasite from one animal to another, without getting any harm. There are different diseases in humans associated with different species of Rickettsias and the arthropods that carry them:
Typhus is caused by Rickettsia prowazekii and transmitted by body or head lice.
Murine typhus is caused by Rickettsia typhi, transmitted by fleas.
Rickettsia rickettsii is normally transmitted by ticks causing Rocky Mountain spotted fever
After the first meiotic cell division ___________
a. two haploid gametes are produced
b. cells are produced that contain twice the same number of chromosomes as somatic cells from which they came.
c. the number of chromosomes will vary depending on how the paternal and maternal chromosomes align at the metaphase plate.
d. DNA replication occurs.
e. None of the above
After the first meiotic cell division, a) two haploid cells are produced, which have half the number of chromosomes compared to the original diploid cell. These cells are not gametes yet; DNA replication does not occur after the first division.
After the first meiotic cell division, a) two haploid cells are produced. This division, known as Meiosis I, separates homologous chromosomes into two new cells. It's important to note that these two cells are not yet gametes, as a second division (Meiosis II) is required for that. Meiosis I is preceded by a phase of DNA replication during the S-phase of the cell cycle, and this replication is crucial as it ensures that each chromosome consists of two identical sister chromatids which are later separated during Meiosis II. The number of chromosomes in the daughter cells after Meiosis I is halved compared to the original diploid cell, and the resulting cells are haploid. The distribution of maternal and paternal chromosomes during Meiosis I is random, leading to genetic variation. As for DNA replication, it does not occur after the first meiotic division; it occurs before Meiosis I begins.
Explain how a genetic map (in map units) is related to actual physical distance (in base pairs of DNA).
Explanation:
A map unit [or centimorgan (cM)] is a unit for measuring genetic linkage. It is defined as the distance between chromosome positions for which the expected average number of intervening chromosomal crossovers in a single generation is 0.01. Its relation with actual physical distances is inconsistent because the number of base pairs to which it corresponds varies widely across the genome, it also depends on whether the meiosis in which the crossing-over takes place is a part of male or female genes (female genome is 4782 cM long, while the male genome is only 2809 cM long).
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Genetic maps show the relative positions of genes using centimorgans as a measure of the likelihood of recombination, while physical maps show actual distances in base pairs. The conversion between cM and bp varies by organism and chromosome region. Three main methods—cytogenetic, radiation hybrid, and sequence mapping—are used to create physical maps.
A genetic map indicates the relative positions and distances between genetic markers or genes on a chromosome. These distances are expressed in map units or centimorgans (cM), which approximate the probability of recombination occurring between these markers during meiosis. A physical map, on the other hand, provides the actual physical distance between genetic markers, measured in the number of base pairs (bp).
It is essential to understand that one map unit does not correlate to a fixed number of base pairs across all species or even all regions of a chromosome. For example, in Arabidopsis, a model organism in plant biology, 1 cM is roughly equivalent to 150,000 base pairs. This variation is due to differing recombination frequencies across the genome; areas known as 'crossover hot spots' experience more frequent recombination, while regions of heterochromatin may show less. To construct physical maps, methods like cytogenetic mapping, radiation hybrid mapping, and sequence mapping are employed.
Bacteria perform the following ecological roles. Which role typically does not involve symbiosis?
a. skin commensalist
b. decomposer
c. gut mutualist
d. pathogen
Answer: Decomposer
Explanation:
Bacteria feed on the dead and decaying organism, in which they feed on them and obtain energy from them.
It is not a mutual relation because the host cell on which they feed is not alive. They eat the organic matter that is present in environment.
The bacteria and fungi clean the environment in this way. The dead plants and animals are decomposed in the environment and the nutrients get back into the soil.
hence, the correct answer is option B
The role that typically does not involve symbiosis is: b. decomposer.
Decomposer bacteria play a vital ecological role by breaking down organic matter and recycling nutrients, but this role typically does not involve symbiosis. Decomposers, like saprophytic bacteria, act independently as they break down dead plants, animals, and organic material, helping to release nutrients back into the ecosystem. In contrast, the other roles mentioned involve symbiotic relationships.
Skin commensalist bacteria coexist harmlessly on the skin, gut mutualist bacteria aid in digestion within the host's intestines, and pathogenic bacteria cause diseases in their host organisms. These interactions represent various forms of symbiosis, where two or more organisms live in close association, often with one benefiting while the other may be harmed or unaffected. So option b is correct.
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Which of the following does not
describehemoglobin?
a.) It binds less tightly to oxygen
thanmyoglobin.
b.) It is a multi-subunit protein with four heme
groupsfor oxygen binding.
c.) 2,3-bisphosphoglycerate increases its affinity
foroxygen.
d.) Maternal hemoglobin has a lower affinity for
oxygenthan fetal hemoglobin.
e.)none of the above.
Answer:
C
Explanation:
All statements describe hemoglobin for the exception of option C.
2,3 biphosphoglycerate (2,3 BPG) its used by erythrocytes to DECREASE affinity for oxygen to unload it to the cells. When the erythrocyte goes to high-metabolic demand areas (the ones that in most need for oxygen) synthesis of 2,3 BPG increases, affinity for oxygen then decreases, and oxygen detach from hemglobin and goes into the tissues.
What are the three functions of the DNA molecule?
A. Reproduce, correct mistakes, produce new DNA
B. Replicate, correct mistakes, produce proteins
C. Replicate, mutate, produce proteins
D. Reproduce offspring, mutate, produce proteins
E. Replicate, mutate, build cells
Answer: Option C- Replicate, Mutate, Produce proteins.
Explanation:
DNA can be defined as Deoxyribonucleic Acid, which is known as the hereditary material in humans as well as in almost all other organisms. Synthesis of DNA proceeds from Deoxyribonucleotides with the help of enzymes called DNA polymerase.
The essential property of DNA is Replication, which means it can make copies of itself to pass on the genetic information and thus it is known as the hereditary material.
Sometimes during replication DNA can undergo certain errors or damage which leads to Mutation. Mutations may or may not lead to abnormal biological processes.
Another function of DNA is Transcription, the process through which synthesis of proteins is done. In this DNA makes mRNA in order to make protein.
Thus, the most suitable answer is "Option C".
The three functions of the DNA molecule are to reproduce offsprings, mutate, produce proteins
In order words, DNA carries genetic instructions and informations in all living organisms.
It contains instructions needed for an organism's reproduction, development and survival
What is DNA?DNA also known as deoxyribonucleic acid and is made up of chemical building blocks called nucleotides.
Structurally, every DNA is made up of three major components; which are as follows:
A phosphate groupA sugar group And one of four types of nitrogen basesLearn more about DNA:
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If 30% of the bases in human DNA are A, (a) what percentage are C? (b) What percentage are T? (c) What percentage are
Answer:
DNA is present as genetic material in all the living organism except some virus. DNA structure follows the Chargaff's rule in which states that the ratio of pyrimidines to purines is equal to 1.
So, amount of adenine will be equal to thymine. If adenine is 30% then thymine is also 30%. Total amount of DNA is 100%. Cytosine and thymine are also equal in the DNA molecule. The total amount of cytosine and guanine is 40%. The amount of cytosine is 20% and the amount of guanine is also 20%.
Thus, thymine is 30%, cytosine is 20% and guanine is 20%.
What are potential hypotheses (explanations) regarding why there are ecological equivalents between many metatherians and eutherians? Discuss your hypothesis in terms of the processes that could lead to the current ecologies and distributions of metatherians and eutherians.
Answer:
by the needs of each specie
Explanation:
Biologist think that the metatherians are close related with marsupials, not just for the adaptive conditions, but also because their teeth.
The eutherians are close related with the placentarian animals, the main reason of the differences is the disposition of teeth.
The hypothesis will be related to the teeth, depending the shape and the position in the mouth, make that the animals prefer to eat different food, and with the passing of time they evolve in one or other group.
This family of bacteria is often associated with urinary tract infections?
A) Listeria
B) Salmonella
C) Proteus
Answer:
The correct answer is C) Proteus
Explanation:
Proteus comes under the family Enterobacteriaceae and is often associated with urinary tract infections in animals and humans. These bacteria are often the part of intestine but become pathogenic when enter into urinary tract.
Proteus mirabilis is a gram negative anaerobic bacteria present as normal flora of intestine known to cause urinary tract infections in humans but most of the urinary tract infection is caused by E. coli.
When these bacteria get into the blood stream they can cause systemic inflammatory response syndrome and sepsis which has very high mortality rate.
Final answer:
The family of bacteria often associated with urinary tract infections is Proteus. While not included in the options, Escherichia coli is the most common cause of UTIs.
Explanation:
The family of bacteria often associated with urinary tract infections (UTIs) is Proteus. Among the options given, Proteus specifically refers to a genus of bacteria that can cause infection in the urinary tract. While not included in the given options, it is noteworthy that Escherichia coli is actually the most common cause of UTIs. Bacteria from the genus Proteus are known for their ability to produce a strong odor and have the ability to form stones in the kidney due to the production of urease, causing further complications.
Sketch a section of a phospholipid bilayer of a membrane, and label the hydrophilic head and hydrophobic tail of one of the phospholipids.
Answer:
The hydrophobic tails are sandwiched in between because they are ‘water-hating’ leaving the hydrophilic ends (which are ‘water-loving’) to interact with the watery environment inside and outside of the cell. The hydrophobic ends are mainly made of fatty acid chains ( and have no charges) while the hydrophilic ends are made of phosphate molecules that are negatively charged.
A phospholipid bilayer, a key component of a cell membrane, comprises two layers of phospholipids each with a hydrophilic (water-attracting) head and a hydrophobic (water-repelling) tail. The bilayer formation allows the cell to create a barrier and maintain different environments on each side.
Explanation:The phospholipid bilayer of a membrane is composed of two layers of phospholipids. Each phospholipid has a hydrophilic head and a hydrophobic tail. The hydrophilic head is attracted to water and is located on the outer sides of the bilayer, in contact with the aqueous (water-based) environment. The hydrophobic tails, however, are repelled by water and are oriented towards the middle of the bilayer away from the water. This unique arrangement allows the phospholipid bilayer to function as a barrier between the inside and outside of a cell, or between different compartments within a cell.
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Which of the following does not occur during mitosis?
a. condensation of the chromosomes
b. replication of the DNA
c. separation of sister chromatids
d. spindle formation
Answer:
Option (b).
Explanation:
Mitosis may be defined as the process of cell division in which a single parent cell divides into two cells. This division is known as reduction division because the chromosome number remains the same.
The chromosome condensation, spindle formation and sister chromatid separation occurs in mitosis. The replication of DNA occurs in the synthesis phase of cell cycle not during the process of mitosis.
Thus, the correct answer is option (b).
Replication of the DNA does not occur during mitosis.
Explanation:The correct answer is b. replication of the DNA. DNA replication occurs during interphase, which is the phase before mitosis. During mitosis, the DNA has already been replicated and is condensed into visible chromosomes. The other events listed in the options all occur during mitosis: condensation of the chromosomes, separation of sister chromatids, and spindle formation.
NADPH is produced in the light independent reaction.
a. True
b. False
Answer:
Given statement is true.
Explanation:
The energy molecules NADH and ATP are produced in light reaction which comprises of series of chemical and photo chemical reactions. These light dependent reaction takes place in the stroma of the chloroplasts. With in the stroma, carbon dioxide is produced from carbohydrates along with formation of glyceraldehyde 3-phosphate there by producing two energy molecule such as ATP and NADH.
Hence, the given statement is true.
Variant Creutzfeldt-Jakob disease, listeriosis, anthrax, and E.coli 0157-H7 infections all have which of the following in common?
a. All four diseases can be transmitted from cattle to humans
b. All four diseases are caused by bacteria
c. All four diseases can be treated with antibiotics
d. All of the above are true for all four diseases.
Answer:
A. All four diseases can be transmitted from cattle to humans
Explanation:
Variant Creutzefeldt Jakob disease (VCJD) is a brain disease caused by a mutated protein (prion).
This particular type of CJD can be caused by eating beef from animals that were infected with bovine spongiform encephalopathy.
Listeriosis is caused by a bacteria called Listeria monocytogenes
Listeriosis often occurs through digesting contaminated foods such as raw meat, beef or dairy products.
E.coli-0157:H7
E. coli is a bacteria that occurs naturally in the digestive system of humans and animals.
However, it can be disease causing once it spreads to other parts of the body.
There are different strains of E.coli.
E.coli 0157:H7 is a dangerous strain to humans and is found in the manure of cattle, dogs and geese.
People can become sick with this by eating raw contaminated meat.
Anthrax
Anthrax is caused by a bacteria called Bacillus Anthracis.
Anthrax mainly affects livestock (cattle) and wild animals.
Anthrax is transmitted to humans by direct contact with an infected animal.
In a nucleosome, the DNA is wrapped around
a. histones.
b. ribosomes.
c. polymerase molecules.
d. a thymine dimer.
Answer:
a. histones. is the correct answer.
Explanation:
In a nucleosome, the DNA is wrapped around eight histones proteins to create strong loops termed nucleosome.
A nucleosome is the structural subunit of the chromatin.
Chromatin is a fiber polymer of double-stranded DNA which is composed up of a nucleosome core. The nucleosome core is made of histone proteins
Each nucleosome is composed of DNA enclosed around eight histone proteins which are called histone octamer.
Beadle and Tatum used which of the following organisms to support their one gene - one enzyme concept?
a. escherichia coli
b. drosophila
c. neurospora
d. salmonella
e. homo sapien
Answer:
Neurospora.
Explanation:
Beadle and Tatum experiment shows one gene one enzyme hypothesis. According to this, a single enzyme is encoded by each gene. This idea is not accepted in today's world.
Beadle and Tatum performed experiment on the neurospora. They chosed neurospora in their experiment because neurospora shows the fast life cycle with alternation of generation. The genetic experiments can be easily performed on neurospora.
Thus, the correct answer is option (c).
The amount of net secondary productivity cannot exceed the amount of net primary productivity.
a. True
b. False
Answer:
True
Explanation:
The net secondary productivity refers to the net amount of energy available to produce biomass at the consumer level. The energy available in the plant tissues after cellular respiration represents the net primary productivity. The net primary productivity represents the rate of incorporation of organic matter into the plant tissues. Hence, net primary productivity is the source of energy and organic matter for the net secondary productivity.
A part of the net primary productivity consumed by a herbivore is used in cellular respiration and other processes and the rest becomes available for biomass accumulation.
Due to the consumption of the part of the net primary productivity for vital processes at the consumer level, the amount of energy available for biomass accumulation, the net secondary productivity, is always less than the NPP.
Which of the following is likely NOT a common feature shared among all living organisms?
All living organisms share a common set of biological molecules.
All living organisms maintain some level of homeostasis.
All living organisms have evolved over the course of many generations.
All living organisms grow.
All living organisms are composed of similar structures.
Answer:
"All living organisms are composed of similar structures."
Explanation:
Living beings must comply with a series of characteristics to be considered as such.
A living being emerges as the result of a very precise organization. Although all living things are formed from the same biological molecules, their degree of organization can differ greatly between different organisms. Thus, there are different levels of organization where we will find multicellular organisms formed by a single cell. Likewise, among the multicellular organisms we find very different structures (as examples of this we can mention a plant, an insect, a starfish and a mammal, all with very different levels of complexity).
We can say that organisms maintain a certain level of homeostasis, they have been adapting to environmental changes over many generations, all organisms grow and reproduce and also have the ability to respond to stimuli.
Lysosomes are membranous orgahelles that contain digestive enzymes. Lysosones can function inside the cell, where their enzymes digest particles taken in by endocytosis or worn-out cell components Lysosomes can also release their enzymes outside the cell, where the enzymes break down extracellular material.
Answer the following questions about conditions related to lysosomal function.
l-cell disease is a lysosomal storage disease that results in the buildup of carbohydrates, lipids, and proteins as inclusion bodies within the cell. Which is the probable cause?
(A) The cell does not take up food molecules by endocytosis.
(B) Lysosomes accumulate extra lipid-digesting enzymes
(C) The lysosome cannot fuse to the cell membrane to release enzymes extracellularly
(D) The Golgi apparatus cannot target the appropriate enzymes to the lysosome.
Answer:
(D) The Golgi apparatus cannot target the appropriate enzymes to the lysosome.
Explanation:
Enzymes are a type of protein build in ribosomes. The rough endoplasmic reticulum works with the golgi apparatus where proteins can be modified, sort and packed according to cell needs. Lysosomes are formed by budding of the Golgi apparatus.
The Golgi apparatus cannot target the appropriate enzymes to the lysosome is correct answer for this question.
Explanation:l-cell disease, also known as lysosomal storage disease, is typically caused by defects in the lysosomal enzymes that are necessary for the breakdown of certain molecules. Thus, the probable cause for the accumulation of carbohydrates, lipids, and proteins in the cell is option (D) The Golgi apparatus cannot target the appropriate enzymes to the lysosome. The Golgi apparatus has a crucial role in the sorting and modification of proteins, including lysosomal enzymes. If it is unable to correctly direct these enzymes to the lysosome, digestion of these molecules within the lysosome will not occur, resulting in their accumulation within the cell.
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Describe the four ways that drugs can affect a person's nervous system.
Answer:
Four ways by which drugs can affect the nervous system are as follows:
Drugs like heroin can mimics the chemical structure of the neurotransmitters. They causes the excess activation of neurons in the brains and affect the nervous system.
Some drugs also mimics the neurotransmitter but causes the abnormal messages sent through the brain. Their mimicry of neurotransmitters cannot activate the neuron but causes the interruption and wrong messaging in the nervous system.
Drugs like cocaine causes the stimulation of release of large number of neurotransmitters. This causes the prevention of recycling of brain chemicals and disturbs the neuron communication.
Some drugs causes the inhibition of release of neurotransmitters in the brain. This stops the signalling of the nervous system and interrupts the chemical messages of the body.
The first strong evidence for colinearity between a gene and its polypeptide product resulted from studies by:
a. Wilhelm Johannsen
b. Gregor Mendel
c. Charles Yanofsky
d. James Watson
e. Francis Crick
Answer:
The correct answer is option c, that is, Charles Yanofsky.
Explanation:
An American geneticist, Charles Yanofsky, worked as a faculty at Stanford University took part in the development of one gene-one enzyme hypothesis, and found attenuation, that is, a riboswitch mechanism.
In the mechanism, the messenger RNA modifies its shape in response to a small molecule, and therefore, changes its binding capability for the regulatory region of an operon and a gene. His studies suggested that genes and proteins are co-linear. If the section of the intron in the gene gets mutated, then the protein generated by the protein also gets mutated.
All the organisms on your campus make up
a. an ecosystem.
b. a community.
c. a population.
d. a taxonomic domain.
All the organisms on your campus make up a community. The correct option is (b).
Understanding Community of OrganismsA community refers to all the populations of different species that coexist and interact in a particular area. It includes all the living organisms, such as plants, animals, fungi, and microorganisms, that inhabit a specific location or ecosystem.
An ecosystem, on the other hand, encompasses both the community of organisms and their physical environment, including abiotic factors like soil, water, and climate.
A population refers to a group of individuals of the same species that live in the same area and have the potential to interbreed.
A taxonomic domain, also known as a superkingdom, is a high-level classification category in the hierarchical system of taxonomy. It is a broader classification than the others mentioned and does not specifically refer to the organisms present on a campus.
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When considering all the organisms on your campus, you're referring to a biological 'community'. This includes diverse species interacting within the same location. It does not refer to an ecosystem, a population, or a taxonomic domain.
Explanation:The organisms found on your campus would comprise what we refer to as a community. This term implies that various species live together and interact in many ways. For example, this community includes everything from students and teachers (humans), to birds, insects, plants, and microbial life forms. It fits perfectly the concept of a community as per biology, because it encompasses an assortment of life forms sharing the same geography. On contrast, an ecosystem would also include inanimate elements like temperature, humidity, soil, etc. A population refers to a group of individuals from the same species living in a specific area. Whereas, a taxonomic domain is a high-level classification of life forms.
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While carbohydrates and proteins are necessary for a healthy diet, fats should be avoided whenever possible.
a. True
b. False
Answer:
false
Explanation:
as long as you don't have too much fat you are fine
One stage in the lysogeniclife cycle has been shown to cause
dramatic
changes in the phenotype and pathogenicity of bacteria (e.g
makingbacterium
cause botulism). What stage is this?
Answer:
In the stage of integration of the viral DNA into the host's cell, it is created the prophages. In this interaction, lysogenic conversion may occur, when a prophage induces a change in the phenotype of its host
Explanation:
The lysogenic cycle is a stage of reproduction of some viruses that infect bacteria, inserting their DNA into the bacterial cell. Together with the lytic cycle, they make up the two cycles of viral reproduction.
In the lytic cycle, the genetic material inserted synthesizes RNA that will form the capsids of the new phages and will eventually cause lysis and cell death. In the lysogenic cycle, viral DNA is integrated into the genome of the bacteria. The bacteria will live and reproduce, also replicating viral DNA in new bacteria without the virus manifesting itself. At the moment in which the DNA of the virus separates from the genome of the bacterium, the lytic cycle begins.
In the process of integrating the viral DNA into the bacterial genome, changes in the phenotype of the bacterium, generally associated with its pathogenicity, can occur, to increase the host's survival capabilities, this process is called lysogenic conversion. Even a non-pathogenic bacterium can permanently become pathogenic by lysogenic conversion.
Factors that should be considered in evaluating a biofuel include (choose any/all that apply, points deducted for incorrect answers):
a. should not compete with food production
b. net energy balance
c. energy balance ratio
d. total energy output
e. economic viability
f. should be carbon negative or neutral
g. should be carbon positive
Answer:
The following are the factors, which should be taken into account while evaluating a biofuel include:
a. Net energy balance
b. Should not compete with the production of food
c. Economic viability
d. Energy balance ratio
e. Should be neutral or carbon negative
The first generation biofuel is generated from sugarcane, which produces ethanol, and this eventually results in the elevation of grain prices. There was a controversy regarding the generation of raw material for its application as food or fuel.
Thus, it should not be competition with the production of food. The bio-fuels are generated with an objective to provide environment of zero carbon emission, that is, should be neutral or carbon negative, and at the same time it should be of low cost in production.
Josey wants to look at the cells of an onion under a light microscope. She peels off a thin, transparent layer of onion and places it on a
microscope slide. Josey places the sample on the microscope stage, looks through the eyepiece, and adjusts the stage to focus the image
However, she is unable to see any details of the cells.
Which of the following possible solutions could possibly help Josey to see the onion cells in detail?
A. Josey should use a thicker piece of onion for her sample
B. Josey shouldhplace her onion sample in a vacuum.
C. Josey should place a drop of water on her sample
D. Josey should apply a stain, such as iodine, to her sample
Answer:
D
Explanation:
A cell and its organelles are usually transparent hence hard to discern without staining. There are different staining techniques that are useful for viewing various type of cells and organelles depending on which stain they pick up well. In this case of an onion, the starch molecules in the onion will take up the iodine and improve visualization. This due to the fact that iodine molecules get emended in the structure of the amylose and amylopectin molecules of starch causing starch molecules to turn blue lack (due to a change in light absorption spectra of the complex).
Final answer:
Josey should try applying a stain, such as iodine, to her onion sample to see the cells in detail. Using a thicker piece of onion, placing the sample in a vacuum, or adding a drop of water can also improve visibility, but applying a stain is the most effective solution.
Explanation:
To see the onion cells in detail, Josey should try applying a stain to her sample. Stains like iodine can help to make the cells more visible under the microscope. By adding a stain, the cells will appear darker or have a different color, making it easier to see their structures and details.
Using a thicker piece of onion for the sample or placing the sample in a vacuum will not help Josey see the onion cells in detail. A thicker piece of onion will not necessarily enhance the visibility of the cells, and placing the sample in a vacuum is not necessary for observing cells under a light microscope.
Adding a drop of water to the sample can actually help improve the visibility of the cells. Water can help to enhance the contrast between the cells and the microscope slide, making the cells easier to see.
Which of the following statements is not true about mRNA?
a. prokaryotic mRNA may contain multiple structural genes on the same transcript, known as polycistronic mRNA.
b. eukaryotes only transcribe one gene at a time on mRNA, called monocistronic mRNA.
c. some eukaryotes are capable of having polycistronic mRNA.
d. eukaryotes almost always produce polycistronic mRNA.
e. the genes for metabolic pathways in bacteria are typically located close together and transcribed on one mRNA.
Answer:
The correct answer is d. eukaryotes almost always produce polycistronic mRNA
Explanation:
In eukaryotes one transcription unit contains the information of only one gene which codes for only one protein or polypeptide therefore eukaryotic mRNA is called monocistronic mRNA.
In prokaryotes transription unit contains set of genes adjacent to each other which are transcribed together and codes for multiple proteins. So prokaryotic mRNA is called polycistronic mRNA.
Almost all messenger RNA present in eukaryotes are monocistronic mRNA because eukaryotes are more complex than prokaryotes and require modification at many stages which is easily possible with monocistronic mRNA.
Explain the importance of Mendel's inclusion of reciprocal crosses within his controlled breeding program of pea plants.
Answer:
Reciprocal cross may be defined as the cross done by reversing the parent genotype. The reciprocal cross was performed by Mendel's during the pea plant experiment.
Mendel's reciprocal cross is important as it determines the contribution of the male or female in the particular trait. He reversed the male and female trait, cross them, whether the male or female is responsible for the transmission of the trait. He found that the progeny of the reciprocal cross are similar as the normal cross. Thus, he concluded that both the parents contribute equally in the transmission of trait.
In four-o'clocks, the allele for red flowers is incompletely dominant over the allele for white flowers, so heterozygotes have pink flowers. What ratios of flower colors would you expect emong the offspring of the following crosses: (a) pink x pink, (b) white x pink, (c) red x red, (d) red x pink, (e) white x white, and (f) red x white? If you specifically wanted to produce pink which of these crosses would be most efficient?
Answer: Crossing red with white is the most efficent way to produce pink flowers.
Explanation:
Let's call the "red" allele R and the "white" allele r. A red flower would have both copies of R, and its genotype would be RR, a white flower would have both copies or r, being rr, and a pink flower would be Rr (heterozygote).
We can represent crosses between individuals by Punnet squares. From pink flowers you can get gametes R and r, from red flowers you can get only R gametes and from white flowers only r. If we put male gametes in the first row and female gametes on the first column, we get the following cases:
a: Crossing pink with pink, we get a ratio of a red flower to a white flower to two pink flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & R & r \\ \ R & RR & Rr \\ \ r & Rr & rr \\ \end{tabular}\end{center}[/tex]
b: Crossing white with pink, we get two pink flowers, and two white flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & r & r \\ \ R & Rr & Rr \\ \ r & rr & rr \\ \end{tabular}\end{center}[/tex]
c: Crossing red with red, we get only red flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & R & R \\ \ R & RR & RR \\ \ R & RR & RR \\ \end{tabular}\end{center}[/tex]
d: Crossing red with pink, we get a ratio of two pink flowers to two red flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & R & R \\ \ R & RR & RR \\ \ r & Rr & Rr \\ \end{tabular}\end{center}[/tex]
e: Crossing white with white, we get only white flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & r & r \\ \ r & rr & rr \\ \ r & rr & rr \\ \end{tabular}\end{center}[/tex]
f: Crossing red with white, we get only pink flowers.
[tex]\begin{center}\begin{tabular}{ |c|c|c|c| }\ & R & R \\ \ r & Rr & Rr \\ \ r & Rr & Rr \\ \end{tabular}\end{center}[/tex]
Thus crossing red with white is the most efficent way to produce pink flowers.
In four-o'clock flowers, incomplete dominance results in pink flowers when red is crossed with white. The offspring ratios vary with different crosses: pink x pink yields 1 red : 2 pink : 1 white, red x white produces all pink offspring, which is the most efficient cross for producing pink flowers.
Explanation:In four-o'clocks, there is a pattern of inheritance known as incomplete dominance, where the allele for red flowers is incompletely dominant over the allele for white flowers, resulting in pink flowers in heterozygous plants. According to Mendelian genetics, we can predict the outcomes of various crosses.
(a) pink x pink (RW x RW): The expected ratio would be 1 red (RR) : 2 pink (RW) : 1 white (WW).(b) white x pink (WW x RW): The expected ratio would be 1 pink (RW) : 1 white (WW).(c) red x red (RR x RR): All offspring would be red (RR).(d) red x pink (RR x RW): The expected ratio would be 1 red (RR) : 1 pink (RW).(e) white x white (WW x WW): All offspring would be white (WW).(f) red x white (RR x WW): All offspring would be pink (RW).If you specifically wanted to produce pink four-o'clock flowers, the most efficient crosses would be red x white (RR x WW) because all offspring would be pink (RW), and there would be no variation in flower color among the progeny.