Answer:
The formation of sex cells.
Explanation:
Meiosis is the process of cell division in which a single parent cell divides to form the four daughter cells. The meiosis division is also known as reduction division.
The meiosis is generally important in the sex cells. The sex cells contains the half number of chromosome as compared with the somatic cells. This type of reduction division occurs in the process of meiosis. The sex cells are haploid cells that are produced by the process of meiosis.
Thus, the correct answer is option (b).
Answer:
The most important function of meiosis is the formation of sex cells.
Explanation:
Meiosis is the process of cell division which produced haploid cells from diploid parent cells. It is called heterotypic cell division. This occurs in germ cells only.
In sexually reproducing organisms, male and female gametes fuse to form a diploid (2n) zygote. If the zygote had the same number of 2n chromosomes as somatic cells, then the zygote has a double number of chromosomes in each generation.
In reality, it does not happen. This is because of the meiotic division. It reduces the chromosome number into half. Thus fertilization does not double the chromosome number in the zygote. Meiotic division counteracts the effect of fertilization.
Meiosis occurs only in sexually reproducing organisms. In this division synapsis of homologous chromosomes takes place. The meiosis results in tetrads at the end and crossing over occurs in this division. The genetic constituents of daughter cells differ from the parent cell.
Growth of the individual from a small body to large body, and repair of wounds occur by mitotic cell division.
What is the oxidizing agent in the following reaction?
Pyruvate + NADH + H+ → Lactate + NAD+
a. oxygen
b. NADH
c. lactate
d. pyruvate
Answer:
The answer is d. pyruvate
Explanation:
An oxidizing agent is the substance that gains electrons in a chemical reaction. At the end of the reaction it is reduced and its oxidation state increased.
A reducing agent is the substance that loses electrons in a chemical reaction. At the end of the reaction it is oxidized and its oxidation state decreased.
Pyruvate gains one electron, it is reduced from pyruvate to lactate; thus, pyruvate is the oxidizing agent.
NADH loses one electron, it is oxidized from NADH to NAD; thus, NADH is the reducing agent
Pyruvate is the oxidizing agent in the reaction.
An oxidizing agent is an element or a compound that gains electrons from another species of the reduction-oxidation reaction.
What are the agents in the reactions?Pyruvate is an oxidizing agent as it acquires electrons in the reaction and gets reduced in the reaction resulting in an increased oxidation state. It gained an electron and gets reduced to lactate.
The substances that lose an electron in a redox reaction is called reducing agent. NADH is a reducing agent as it lost one electron and gets oxidized from NADH to [tex]\rm NAD^{+}[/tex].
Therefore, option d is an oxidizing agent.
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Which of the following is an advantage to co-evolving with a pollinator, rather than using wind pollination?
a. Pollinators require more energy to attract
b. Pollinators reduce the chance of hybridization
c. Pollinators are susceptible to climate change and deforestation
d. Pollinators rely on the flowers for food and have to pollinate to survive
Answer:
d. Pollinators rely on the flowers for food and have to pollinate to survive
Explanation:
Insect pollination is more successful as compared to wind pollination which is completely a chance event. Insect pollinated plants have evolved several strategies to attract pollinators.
The co-evolution of insect-pollinated plants further ensures the mutualism between them. Pollinators derive their food from the flowers they visit in the form of nectar.
Due to their food requirements, insects visit the flowers and in turn pollinate them. If insects do not visit the flowers, they will face the food scarcity. To ensure food availability, insects visit the flowers and pollinate them.
Final answer:
The advantage to co-evolving with a pollinator rather than relying on wind pollination is that pollinators rely on the flowers for food and have to pollinate to survive.
Explanation:
The advantage to co-evolving with a pollinator rather than relying on wind pollination is that pollinators rely on the flowers for food and have to pollinate to survive (option d). This means that the pollinators actively seek out and visit flowers, increasing the chances of successful pollination. In contrast, wind pollination relies on chance and the movement of air to carry pollen from one flower to another, which is less efficient.
Which (if any) of the following statements about the major histocompatibility complex (MHC) is not correct?
If all of the statements are correct choose the last answer.
a. all human cells, including red blood cells, possess MHC I
b. each person has a unique MHC (except for identical twins).
c. in order for organ transplantation to be successful, the organ donot and the recipient must have a similar MHC
d. the MHC allows the immune cells to differentiate the host cells from "foreign" cells
e. all of the above statements about the MHC are correct.
Answer:
a. all human cells, including red blood cells, possess MHC I
Explanation:
MHC is a group of genes involved in the immunological recognition of self (cells of the organism) and nonself (exogenous agents), it's found un all nucleated cells of the body, this means it can't be found in red blood cells because they lack a nucleus.
MHC genes are highly polymorphic, this means different alleles exist in different individuals except for identical twins that share the same genetic profile.
When transplantation happens, the organ donor and receiver need to have similar MHC, otherwise, the receptor's dendritic cells will recognize the new organ as non-self molecules. Since MHC are highly polymorphic, choosing a sibling as a donor increases the chances to find a match since the receptor shares genetic information with the donor.
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Which of the following descriptions about the different forms of DNA is not correct?
a. A-DNA has a deeper major groove then B-DNA
b. There are 10.5 base pairs per helical turn in B-DNA
c. Z-DNA is a zigzag left-handed helix
d. Z-DNA is favored in sequences with long repeats of purines alternating in the syn- and anti-conformation.
e. A-DNA is favored in solutions relatively devoid of water.
Answer:
Option (d).
Explanation:
DNA is the genetic material of the living organisms (except few viruses). Three different forms of DNA are A-DNA, B-DNA and Z-DNA. B form of DNA is more common and stable form of DNA.
Z-DNA has the ability to form in the junctions between the B-DNA. The Z DNA has both syn and anti conformation favored by the long repeats of the alternating purines and pyrimidine sequences. Only the pyrimidine sequences are not favorable for the Z-DNA structure.
Thus, the correct answer is option (d).
Describe in detail the lifecycle of Cryptosporidium.
Answer:
The transmission is fecal-oral, by direct contact of the host-host and through water or food contaminated with oocysts, infectious at the time of being eliminated with the fecal matter of the host. It is worth mentioning that cryptosporidiosis has been identified in epidemic outbreaks due to contamination of drinking, surface and recreational water networks.
Explanation:
It is recognized that despite the careful washing of green leafy fruits and vegetables, the oocysts, due to their cover and, therefore, their resistance, can be found in the stoma of these fruits. Cryptosporidium oocysts remain viable in seawater for 1 year. Its concentration in bivalve molluscs has also been documented and there is growing evidence that the parasite can multiply in host-free environments.
Cryptosporidium oocysts, with double wall and 4 naked sporozoites inside, survive in the environment for long periods of time (between 20-30 ° C, for weeks / months). Once in the digestive tract, mainly at the level of the small intestine, the sporozoites (invasive form) are released through a groove in the oocysts in solution.
Sporozoites have an apical complex, which aids in adhesion to the host cell membrane, which involves invasive forms of the parasite and results in a parasitic vacuole. This vacuole, which encompasses the sporozoite in a special extracytoplasmic (epicellular) niche, has an electrodense region at the base, called a feeding organelle or epimerite.
Further development includes the transformation of sporozoite into trophozoite and reproduction asexually, by merogonia (cell division is by endopolinnya: formation of daughter cells by budding), which results in merones of two types: merones I with 8 merozoites, which they invade other cells, with repetition of the cycle and formation of other merons I, or merons II, with 4 merozoites; the latter give rise to sexual stages and sexual reproduction occurs through gametogonia, with micro and macrogamets. The resulting zygotes go through a final stage of development (sporogonia), which culminates in the production of oocysts; Cryptosporidium has two functional types of oocysts: a) thick-walled infectious, with 4 bare sporozoites (no sporocysts), eliminated with feces; b) thin-walled oocysts, involved in intestinal autoinfection
The 3 phases of reproduction cover between 12 and 24 h, with a new generation of parasites and self-infecting forms on each occasion. Given such an amount of organisms, it is not surprising that in immunocompromised subjects, parasitic forms can spread to the bile and pancreatic ducts, the stomach and the respiratory tract.
The DNA consists of __________
a. four strands
b. one strand
c. three strands
d. two strands
Answer:
The correct answer is option D. two strands.
Explanation:
DNA is a genetic molecule that is a basic unit that carries the genetic information for functional, developmental, growth and reproduction of all organisms and many viruses.
DNA has two complementary strands that make a double-stranded segment of DNA that coiled and antiparallel to one another. The antiparallel strands are run in opposite directions to each other but physically parallel. These strands are made up of nucleotide and called polynucleotides. This nucleotide consists of one of four nitrogen bases, a deoxyribose pentose sugar, and a phosphate group.
Thus, the correct answer is option D. two strands.
Answer:
D two strands
Explanation:
The DNA consists of TWO STRANDS
A man has been bitten by a snake. What type of immunization is used to treat him and what is the exact agent? Why is this type of immunization necessary in this case?
Answer:
The type of immunization used is passive, and the exact agent used is an antivenom. This type of immunization is necessary because the man does not have antibodies to fight against the venom's toxins.
Explanation:
To treat from snake bites is necessary to use antivenoms, these are given to the patient as soon as possible after the bite, they consist on a mixture of hyperimmune globulins and other proteins obtained from the serum of animals, usually horses or sheep, previously immunized with the venom of a snake. This kind of immunization is called passive immunization, is temporary and it uses exogenous preformed antibodies to provide treatment to an unprotected individual.
In this case, we use this kind of immunization because the person who was bitten didn't have the previous contact with the snake's venom, this means that the victim does not have antibodies to fight against the toxins in their body.
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Describe four types of point mutations: transitions, transversions, deletions, and additions.
Explanation:
Mutation - any sudden and hereditary change in the genetic set of an organism, which is not explained by the recombination of pre existing genetic variation. Point mutation - Changes in the nucleotide sequence, which alter the amino acid sequence in the polypeptide chain encoded by the gene, leading to a phenotypic change.
When a purine base is replaced by another purine base (A by G or vice versa) or a pyrimidine base is replaced by another pyrimidine base (T by C or vice versa) it is called a transition. In contrast to the transitions we have the so-called transversions, which are mutations where a purine base is replaced by another pyrimidine, or vice versa, that is, a pair C-G is replaced by another A-T or vice versa. It may be a simple substitution of a base pair, which may be by deletion or addition of one or a few bases. Deletion: is the loss of a portion of the chromosome, resulting in the lack of one or more genes
Both the change in the genetic material and the process by which the change occurs is referred to as a/an:
a. mutation
b. error
c. reparation
d. mutation and error
e. recombination
Answer: a. mutation
Explanation:
A mutation is a change or alteration and a process that occurs in the DNA sequence of the organism. This happens due to the mistake in the DNA replication process or because of the environmental factors for example exposure to the UV radiation or due to smoking. These mutations either favors the survival of the organisms or they are lethal for the organisms.
Which of these processes involve enzymes?
a. Sliced apples turns brown from being left on the counter
b. Steak turns brown from grilling
c. Sugar caramelizes at high heat
d. Coffee beans are roasted
Final answer:
Enzymes are involved in the processes of sliced apples turning brown, steak turning brown from grilling, sugar caramelizing at high heat, and coffee beans being roasted.
Explanation:
Enzymes are involved in processes that require a biochemical reaction to occur. In this case, the processes that involve enzymes are:
Sliced apples turning brown from being left on the counter. Enzymes in the apples react with oxygen in the air and cause the browning reaction.Steak turning brown from grilling. Enzymes present in the meat react with heat, resulting in a browning reaction.Sugar caramelizing at high heat. Enzymes present in the sugar facilitate the chemical transformation that leads to caramelization.Coffee beans being roasted. Enzymes in the beans are responsible for producing the desirable aroma and flavor during the roasting process.Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _____ is to _____.
a. exergonic; spontaneous
b. exergonic; endergonic
c. free energy; entropy
d. work; energy
Answer:
exergonic; endergonic.
Explanation:
Exergonic reactions may be defined as the reactions in which the energy is released during the reaction. Endergonic reaction are the reaction in which energy is required for the occurrence of reaction.
Catabolism reaction in which the large substance is broken down into simpler substance. Large amount of energy is released during the reaction and considered as exergonic reaction. Anabolism reaction in which small substance combine together to form a large molecule. A large amount of energy is required in this reaction and considered as endergonic reaction.
Thus, the correct answer is option (b).
Catabolism is to anabolism as exergonic is to endergonic. and the correct option is option B.
Catabolism and exergonic reactions are both types of chemical reactions that release energy. However, there are some key differences between the two.
Catabolism is a type of metabolic reaction that breaks down complex molecules into smaller molecules. This process releases energy, which can be used for cellular processes such as muscle contraction, protein synthesis, and cell growth.
Exergonic reactions are chemical reactions that release energy in the form of heat or light. These reactions are spontaneous, meaning that they occur without the need for an input of energy.
Thus, the ideal selection is option B.
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The large surface area of the alveoli allows for efficient diffusion of oxygen and removal of carbon dioxide from the blood. What is the approximate surface area of the alveoli?
A. 70 miles
B. 7 miles
C. 0.7 square meters
D. 7 square meters
E. 70 square meters
Answer:
The correct option is: E. 70 square meters
Explanation:
Pulmonary alveoli is described as the cup-shaped hollow cavity, found in the alveolar sacs of mammalian lungs.
The alveolar membrane, also called the respiratory membrane, allows the exchange of gases. Across this membrane, carbon dioxide is released from the capillaries into the alveoli and oxygen is diffused from the alveoli into the capillaries.
About 300 million alveoli are present in the lungs of a human, which makes about 70m² of surface area.
What is the molecule of inheritance?
a. DNA
b. RNA
c. protein
d. maltose
Answer:A
DNA
Explanation:
Explain how the nucleolus, ribosomes, endoplasmic
reticulum,Golgi apparats function together in protein
synthesis.
Answer:
The nucleolus refers to a condensed region of chromatin where the production of ribosomes takes place. Ribosomes are the regions of protein synthesis, which perform this function by aligning the amino acids in a suitable sequence, as directed by the messenger RNA.
The ribosomes are generally found entrenched in the endoplasmic reticulum. The production of a huge amount of proteins is possible due to the presence of very large surface area provided by the ER to the ribosomes. The prime function of the ER is to transport the newly formed proteins over to the Golgi apparatus.
The main function of the Golgi apparatus is to amend the proteins and administer them into the vesicles. From here they are mediated towards different cell parts. Hence, the mentioned cell organelles are associated with their activities of synthesis of proteins and transportation.
Garrod's concept regarding the relationship between the gene and metabolism can best be described as:
a. one gene - one polypeptide
b. one mutant gene - one metabolic block
c. one gene - one metabolism
d. one gene - one transcript
Answer:
b. one mutant gene - one metabolic block
Explanation:
Garrod studied inborn errors of metabolism and explained the molecular causes of various genetic diseases such as albinism and alkaptonuria.
Accordingly, the individuals homozygous for the recessive allele exhibit metabolic defect responsible for the disease.
For example, alkapton is normally degraded into maleylacetoacetic acid by the reaction catalyzed by the enzyme homogentisic acid oxidase. A mutation in the respective gene produces nonfunctional enzyme and leads to alkaptonuria as the individuals are not able to degree alkapton in absence of functional enzyme.
Hence, one mutation blocks one metabolic pathway and leads to a genetic disorder.
Sugar changes into energy in
a. golgi bodies
b. mitochondria
c. nucleus
d. nucleolus
Answer:
Mithochondria.
Explanation:
You may have heard the phrase "mithochondria is the powerhouse of the cell". This is because, embedded in the inner mithochondrial membrane, there is a protein that is capable of creating ATP by using the energy that results from dissipating the chemoelectric potencial between the intermembrane space and the mithochondrial matrix, by bombing protons (that came from the degradation of sugar) to the mithochondrial matrix.
The Calvin cycle is considered light-independent because it can occur in darkness. However, most often the Calvin cycle takes place in sunlight.
Which of the following likely explains why?
A) The enzymes involved in the Calvin cycle are unable to bind substrates in the dark.
B) Sunlight is important in activating carbon fixation in the Calvin cycle
C) The Calvin cycle requires ATP and NADPH, which require sunlight to be produced
D) RußP regeneration requires sunlight in order to occur and continue the Calvin cycle.
Answer:
C) The Calvin cycle requires ATP and NADPH, which require sunlight to be produced
Explanation:
The light-dependent phase of photosynthesis includes the photolysis of water molecules. The released electrons are passed to PSII to PSI via electron carriers and finally to NADP+ to reduce it into NADPH.
Transfer of electrons via electron carriers also generates the proton concentration gradient which in turn drives ATP synthesis. ATP and NADPH formed during light reactions are used in the Calvin cycle as an energy source and electron donor respectively.
Hence, to continue, the Calvin cycle requires the synthesis of ATP and NADPH in the presence of light.
Answer:
C
Explanation:
Bruce Ames constructed a mutagenicity test which initially missed carcinogens which were noncarcinogenic to the tester strains. Why?
a. tester strains were more resistant to the mutagenic effects of the carcinogen than eukaryotes
b. not all carcinogens are mutagens
c. potential carcinogens needed to be modified in eukaryotes before they were mutagenic
d. histidine biosynthesis was inhibited by the presence of the carcinogens
e. the organism used in the test is a pathogen of mice
Answer:
C: Potential carcinogens needed to be modified in eukaryotes before they were mutagenic
Explanation:
Previous carcinogenic tests used live animals and costly and time-consuming processes. This rendered animal testing unworkable for use in broad scale screening and lowered the amount of compounds that could be tested.
Ames test utilizes the Salmonella typhimurium bacteria to test for mutagens and is much cheaper and quicker. Since Salmonella is a prokaryote the way bacteria react is different from eukaryotes because they have slightly different mechanisms in the way DNA replicates.
Radiation can cause breaks in human chromosomes. However, insects can survive much higher lecels of exposure. Why?
Explanation:
The influence from radioactivity is inversely proportional to the number of chromosomes , since , humans have more DNA , chromosomes than the insects , and therefore , due to less chromosomes in insects , they are more resistant towards radioactivity .
As the target of the radiation is the DNA .
Hence , It is clear that insect due to lesser DNA are less prone to Radiations .
Blood typing: who can donors donate to and who can receivers receive from? Know the Rh factor and how it relates to Rh antibodies.
Answer:
Karl Landsteiner along with his coworkers recognized four types of blood groups in human beings, commonly called as ABO blood grouping.
Explanation:
The membrane of RBCs possess several antigens. Depending on the nature of antigens on the surface of RBCS various types of blood grouping has been done. Two such groupings are The ABO and Rh grouping and are widely used all over the world.
ABO grouping:
There are four types of blood groups in human beings. ABO grouping is based on the presence or absence of two surface antigens on the RBCs namely A and B. Similarly, the plasma of different individuals also contain two natural antibodies called anti-A and anti-B.
If an antigen is present on the surface of RBCs, the corresponding antibody must be absent from the plasma and if the antigen is absent on the RBCs, the corresponding antibody must be present in the plasma.
Blood group A has A antigen on RBCs and anti-B antibody in plasma
Blood group B has B antigen on RBCs and anti-A antibody in plasma
Blood group AB has A and B antigen on RBCs and no antibody in plasma
Blood group O has no antigen on RBCs and both anti-A and anti-B antibody in plasma
Rh grouping:
Another group of antigens found on the RBCs of most people is the Rh factor. People who have this antigens are said to be Rh+ve whereas those who do not are called Rh-ve. Rh groups should also be matched before transfusion because A Rh-ve person if exposed to Rh+ve blood , will form specific antibodies against the Rh antigen.
The concentration of CO2 in the atmosphere globally (choose any/all that apply, points deducted for incorrect answers):
a. has a greater annual variation in the northern hemisphere than in the southern hemisphere
b. has a greater annual variation in the southern hemisphere than in the northern hemisphere
c. has an annual variation globally that is constant regardless of location
d. varies annually depending on rates of marine NEP
e. varies annually depending on rates of terrestrial NEP
Answer:
a. has a greater annual variation in the northern hemisphere than in the southern hemisphere
Explanation:
These latitudinal fluctuation variations are the consequence of plant photosynthetic activity. As plants begin to photosynthesize in the spring and summer, they consume CO2 from the atmosphere and eventually use it as a carbon source for growth and reproduction. This leads to the decline in CO2 concentrations beginning in May each year. By reducing photosynthesis, crops save energy once winter comes. The dominant method, without photosynthesis, is ecosystem CO2 exhalation (cellular respiration and decomposition), including bacteria, crops, and livestock.
Two latitudes of Earth contain most of land plants: Northern Hemisphere mainlands and the tropics that envelop, among different territories, the immense downpour woods of the Amazon basin. Close to the equator temperature are constant all year long. Shifts in CO2 are hence most articulated in the Northern Hemisphere, where the regular changes in temperature bring about enormous contrasts in plant photosynthesis from summer to winter.
Cyanide cause cellular death because it prevents the electron transport chain from producing ATP.
a. True
b. False
Answer:
The correct answer will be option-true.
Explanation:
Cyanide is a class of molecules which contains CN group in their structure. They are mostly considered deadly poisons as they inhibit ATP synthesis.
The cyanide ions of the cyanide bind with the cytochrome C oxidase enzyme of electron transport chain in mitochondria. The main role of the enzyme is to transfer the electron to the oxygen during electron transport chain.
Since cyanide ions binding prevents the cytochrome C oxidase to perform its function, therefore ATP will not be synthesized in the mitochondria.
Thus, option-true is the correct answer.
All fungi are
a. symbiotic.
b. heterotrophic.
c. flagellated.
d. decomposers
Answer:
b. heterotrophic is the correct answer.
Explanation:
All fungi are heterotrophic because they cannot produce their food, they get their food by consuming organic compounds from the external or environmental sources.
fungi do have chlorophyll pigment and they are not able to produce their food from the sunlight and water.
heterotroph are those who cannot manufacture their food,they depend on external sources to get food and energy.
In DNA technology, the term vector can refer to
a. the enzyme that cuts DNA into restriction fragments.
b. the sticky end of a DNA fragment.
c. a SNP marker.
d. a plasmid used to transfer DNA into a living cell.
Answer:
d. a plasmid used to transfer DNA into a living cell.
Explanation:
In molecular biology, it's very useful to use vectors to insert a DNA fragment of interest into a host cell.
In this technique, a DNA sequence of interest is isolated from a larger DNA molecule or even from a complete genome by cutting the DNA with restriction enzymes. At the same time, the restriction enzymes are used to cut open a plasmid, a circular molecule of DNA that can replicate independently and survive for a certain amount of time in the host cell (how much time, it depends on the cell). The fragment of interest is then linked to open plasmid, forming the vector. The vector can be introduced into a living cell, and the sequence of interest can be analyzed in different ways.
I've attached a diagram made by the University of Waikato that illustrates the procedure for creating a vector.
In DNA technology, a vector refers to a plasmid used to transfer DNA into a living cell.
Explanation:The term vector in DNA technology refers to a plasmid used to transfer DNA into a living cell. Plasmids are small, circular DNA molecules that can replicate independently within a host cell. They are commonly used as vectors to introduce foreign DNA into cells for various purposes, such as gene cloning, gene expression, and genetic engineering.
Plasmid vectors typically contain multiple components, including an origin of replication, selectable markers, and restriction sites. The origin of replication allows the plasmid to replicate autonomously within the host cell, while the selectable markers enable the identification and selection of cells that have taken up the plasmid. The restriction sites, on the other hand, are specific DNA sequences recognized by restriction enzymes, which can be used to cut and insert DNA fragments into the plasmid.
Overall, plasmid vectors serve as important tools in DNA technology as they facilitate the transfer and manipulation of DNA in living cells.
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what is a substance that cannot be broken down to other substances by ordinary chemical means?
Answer:
The correct answer is an element.
Explanation:
An element refers to a component whose atoms comprises a similar number of protons, or it can be said that the atoms of a specific element exhibit the same atomic number. Chemically, they are the simplest components, which cannot be further differentiated by any chemical means. The elements can get converted into other elements with the help of nuclear methods.
All of the following are weak
acidsexcept
A. HCNO.
B. HBr.
C. HF.
D. HNO2.
E. HCN.
Answer:
HBr.
Explanation:
Acids may be defined as the substance that has the ability to release hydrogen ions in the solution. Two types of acids are strong acids and weak acids.
Weak acids do not completely dissociate into ions whereas strong acids has the ability to completely dissociate into ions. Among the acids given in the solution, hydrogen bromide has the ability to completely dissociate into hydrogen and bromide ions. Hence, HBr acts as a strong acid.
Thus, the correct answer is option (B).
E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?
a. one high-density and one low-density band
b. one intermediate-density band
c. one high-density and one intermediate-density band
d. one low-density and one intermediate-density band
Answer:
Option (d).
Explanation:
DNA is the genetic material of all the organism except some viruses. DNA is composed of nitrogenous base, deoxyribose pentose sugar and the phosphate group.
DNA replicatese by semi-conservative mode of replication in which one the daughter DNA consists of one newly synthesized strand and one parental strand. This mode of replication was explained by Messelson and Sthal experiment. The cells from 15N medium are transferred to 14N medium the band of intermediate density was observed. The daughter DNA consists of one 15N DNA strand and one 14N DNA strnd. This strand undergo replication in the 14N medium. This time one low density DNA band ( contains 14N - 14N DNA strand) and one intermediate density band ( 14N-15N DNA).
Thus, the correct answer is option (d).
What is typically attached to the acceptor end of a tRNA?
a. a protein
b. an amino acid
c. a ribosome
d. a nucleosome
Answer:
The correct answer is b. an amino acid
Explanation:
A tRNA is called adaptor RNA which have cloverleaf-like secondary structures. These structures contain stems and loops which make up the acceptor arm, anticodon stem and loop, D- stem and loop, and T- stem and loop.
Acceptor arm contains seven base pairs and four single stranded nucleotide which include conserved CCA sequence. The function of acceptor arm is attach amino acids require for protein synthesis.
The anticodon loop gives information to acceptor to attach a specific amino acid according to the sequence present in mRNA. The first amino acid which attaches to acceptor arm is methionine.
Thus, the correct answer is b. an amino acid.
Describe the outcome of irregular mitosis, meiosis I and meiosis II. be sure use all relevant terminology and to note the impact on chromosomal number in each circumstance.
Answer:
Outcome of irregular mitosis:
Mitosis may be defined as the process of cell division in which a single diploid parent cell divides to form two diploid daughter cells. The irregular mitosis may result in aneuploidy condition of chromosome in which the the extra (trisomy) or missing (nullisomy) of one or more chromosome may occur. This condition also leads the genetic disease and cancer condition. Non disjunction may occur in which the sister chromatid are unable to separate.
Outcome of irregular meiosis I and meiosis II.
Meiosis is the cell division in which a single diploid parent cell divides into four haploid daughter cells. Nondisjunction at meiosis I prevent the segregation at least one homologous chromosomes. This causes the two cells with extra copy of chromosome and two cells with deleted chromosome. Nondisjunction at meiosis II. Two cells have normal chromosomes and two cells with the abnormal (missing and extra) chromosomes.
What are the differences between the endocrine and nervous systems?
Answer:
Explanation:
The endocrine system is a complex of glands that secrete hormones as a chemical messenger. These hormones carry information and instructions throughout the bloodstream from one part of the body to another. These hormones control many body functions such as respiration, sensory perception, metabolisms, growth, reproduction, the mood among others.
On the other hand, the nervous system is made up of neurons that communicate with each other to extend a message (from our own body or the outside) to the brain, for analysis and further decision of what to do with that information. A group of neurons, sensory neurons, respond to several stimuli such as touch, light, and sound to let the brain know about the surrounding environment. Another group of neurons, motor neurons, work inside the body and carry signals to active muscle or glands.