Answer:
The correct answers are e. "all of the above statement regarding smallpox are correct".
Explanation:
Smallpox vaccination is one of the most clear examples of the benefits of performing a global vaccination program, because smallpox has been officially eradicated worldwide in 1980. However, some precautions regarding this disease should be taken, as is a very pathogenic diseases that is spread through respiratory droplets. The smallpox vaccine contains live vaccinia virus and it may revert to pathogenicity, therefore its application should be performed by an expert to assure that the virus does not affect the patient.
Below are steps performed to make an E. coli bacteria that can make human insulin protein for the health care market. List these steps in their proper order.
a. Use heat shock or electroporation to get the recombinant human insulin gene to go into a living E. coli cell.
b. Grow the E. coli in fermentation culture, extract and sell Humulin.
c. Modify the human gene and give it a promoter that will be turned on in E. coli cells.
d. Extract the DNA from a human who does not have diabetes
e. Isolate and clone (make copies of) the gene encoding the insulin protein
Answer:
The following are the steps for making the human insulin protein for the health care market:
1. Obtain the DNA from a human being who does not have diabetes.
2. Modify the human gene, and provide it a promoter, which will get turn on when placed within the E.coli cell.
3. Separate and make copies of the gene encrypting the insulin protein.
4. Application of electroporation or heat shock method in order to administer the human insulin gene within the living E.coli cell.
5. Development and growth of E.coli in the fermentation culture, and then extract and sell the humulin in the market.
a. What are the four major stages of the cell cycle? b. Which stages are included in interphase? c. What events distinguish G1 S, and G2?
Answer:
The 4 major stages of the cell cycle are M phase, G1 phase,S phase, and G2 phase.
The stages includes interphase are G1 phase, S phase, and G2 phase.
Explanation:
The cell cycle is a 4 stage process that leads to cell division. In eukaryotic cells, genome replication is coordinated with the cell cycle. Hence 2 copies of the entire genome are available when the cell divides.
The dividing cells undergo repeated cycles of metaphase, when nuclear and cell division occurs and the interphase where DNA replication occurs combined known as the cell cycle. The 4 stages of the cell cycle are M-phase (mitosis), G1 Phase (gap 1), S-phase (synthesis phase), and G2 phase (gap 2).
The interphase is also known as the resting phase. But it is a preparatory phase for cell division. During this phase, histone proteins are formed and centrioles divide to form 2 new centrioles.
Interphase has 3 phases of the cell cycle except for M-phase. These are the G1 phase, S phase, and G2 phase.
G- phase: It is the postmitotic gap phase. It occurs at the end of the mitotic cell division. RNA and proteins are synthesized in this phase but not the DNA.
S-phase: During this phase, DNA is synthesized. In this period DNA content of the nucleus is doubled.
G2 - phase: This is the premitotic gap phase. Here synthesis of RNA and protein continues. The DNA synthesis stops in this phase.
M-Phase: It is the mitosis period when the nucleus and cell divide.
All human cell division takes 20 hrs to complete. G1 phase takes 9 hrs, and S-phase takes 8 hrs to complete. G2 phase completes in 2 hrs and the M phase takes only 45 min. The G1 and S phase is the longest phase in the cell division.
Final answer:
The cell cycle consists of four major stages: G1, S, G2, and M phase. Interphase, which prepares the cell for division, includes G1, S, and G2. During G1, the cell grows; in S, the cell replicates its DNA; and in G2, the cell prepares for mitosis.
Explanation:
The cell cycle consists of four major stages: G1, S, G2, and M phase. Each of these stages represents a part of the process through which cells duplicate and divide.
Interphase
Interphase is a stage in the cell cycle where the cell prepares for division and includes three phases: G1, S, and G2. During the G1 phase, the cell grows and performs regular functions. The S phase, or synthetic phase, is crucial as the cell replicates its DNA. Finally, in the G2 phase, the cell undergoes further growth and prepares for mitosis.
Distinctive Events of G1, S, and G2 Phases
G1: Cell growth and normal functions continue. It is essentially the cell's preparation phase for DNA replication.
S phase: DNA replication occurs, ensuring that each new cell will have a complete set of genetic information.
G2: Final preparations for mitosis, including further cell growth and production of proteins necessary for cell division.
Mitosis (Cell Division)
Mitosis is the process of dividing the replicated DNA between two new cells. This involves spindle fibers that help segregate chromosomes to opposite sides of the cell. Mitosis comprises several stages leading to the distribution of identical genetic material to daughter cells.
The four major stages of the cell cycle are G1, S, G2, and M phase.
Interphase includes the G1, S, and G2 stages.
The G1 phase is the period of cell growth before DNA replication, the S phase is when DNA replicates, and the G2 phase is when the cell makes final preparations for mitosis.
How would you make 1 Liter of a 1 M solution of CaCl2 (molecular weight =111 g)?
Answer:
Dissolve 111 grams of CaCl2 in 1 Liter of water and it would give 1 M solution.
Explanation:
This is simple, if you want to make 1M solution of any substance just take one mole of that substance and dissolve it in one decimeter cube or one liter of water.
And one mole of a substance equal to the molecular weight of that substance taken in grams.
So you have to dissolve 111 grams of CaCl2 in one liter water and it would make 1 M solution of CaCl2.
To prepare a 1 M solution of a substance, you need to dissolve the molecular weight of the substance (expressed in grams) in enough water to make 1 Liter of solution. Therefore, to make a 1 M solution of CaCl2, dissolve 111 grams of it in less than 1 Liter of water and then add more water until the volume is 1 Liter.
Explanation:To make 1 Liter of a 1 M (Molar) solution of CaCl2(Calcium Chloride), which has a molecular weight of approximately 111g/mol, you would need to dissolve 111 grams of CaCl2 in enough water to make 1 Liter of solution.
This is because the molarity of a solution is defined as the number of moles of solute per liter of solution. In this case, 1 mole of CaCl2 is 111g, so to have 1 M solution, you need 1 mole (or 111g) of CaCl2 per 1 Liter of solution. Therefore, you should add 111g of CaCl2 to less than 1 Liter of water, then add water until the volume reaches 1 Liter.
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If you mixed the mRNA of a human gene with the genomic DNA for the same gene and allowed the RNA and DNA to form a hybrid, what would you be likely to see in the electron microscope? Your figure should include hybridization involving both DNA strands (template and RNA-Iike) as well as the mRNA.
Answer:
Explanation:
A gene in the DNA has both exons and introns. Exons are the coding sequences that will remain in the mature mRNA, and introns are non-coding sequences that are spliced out and are not a part of the mature mRNA.
If you hybridize genomic DNA with a mature mRNA, in a microscope you'll probably see something like the figure I'm attaching. In A you can see a schematic diagram of the mRNA-DNA hybrid; the loops are single stranded DNA containing introns, that are not present in the mRNA and therefore remain unpaired.
In figure B you can see a real image of a mRNA-DNA hybrid and its interpertation below.
The hybridization involving both DNA strands would look like a perfect pairing, because both DNA strands contain complementary sequences of exons and introns.
By mixing the mRNA of a human gene with the genomic DNA for the same gene and allowing them to hybridize, you would likely see the formation of hybrid RNA-DNA molecules under the electron microscope. The hybridization would occur specifically between the mRNA molecule and the template or antisense strand of the genomic DNA. The non-template or sense strand does not hybridize with the mRNA.
Explanation:If you mixed the mRNA of a human gene with the genomic DNA for the same gene and allowed the RNA and DNA to form a hybrid, you would likely see a formation of hybrid RNA-DNA molecules under the electron microscope. This is due to the fact that the mRNA and the template strand (antisense strand) of the genomic DNA are fully complementary.
In the process of transcription, a strand of mRNA is synthesized that is complementary to the gene of interest within the genomic DNA. This complementary nature makes it possible for the mRNA and DNA to hybridize and form a complex under suitable conditions. A gene on the DNA molecule is transcribed into a complementary mRNA molecule, forming a transcription bubble that is visible under the electron microscope.
When you consider both strands of the genomic DNA, the hybridization would occur between the mRNA molecule and the template strand of the genomic DNA. The non-template strand or RNA-like strand which is identical to the mRNA, with the exception of thymine (T) in DNA being replaced by uracil (U) in RNA, does not hybridize with the mRNA. The hydrogen bond formation between the two strands can be observed under an electron microscope.
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Shaun and Sara are studying the states of matter together in science class. Their teacher asks them to list the states of matter and determine in which state the particles move freely. Which statement is correct?
A. There are two states of matter, and particles move freely in the liquids states.
B. There are three states of matter, and particles move freely in the gaseous state.
C. There are four states of matter, and particles move freely in their solid state.
D. There are five states of matter, and particles move freely in both their solid and gaseous states.
Answer:
The B statement is correct. There are three states of matter, and particles move freely in the gaseous state.
Explanation:
State of matter can be described as the different forms in which matter can subsist. Mainly, there are three forms of matter i.e solid, liquid and gases.
Solids are the state of matter in which particles are tightly packed. Due to being tightly packed, the particles in a solid cannot move hence solids have definite shape and volume.
If a solid is heated above it's melting point, it turns into a liquid. The particles in a liquid are not as closely packed as in solids. hence, shape of liquids is not definite.
Gases can be described as state of matter in which particles are free to move. Gases do not have a definite shape or volume.
Answer:
Explanation:
B
What is the primary function of the light reactions of photosynthesis?
A) to produce energy-rich glucose from carbon dioxide and water
B) to produce ATP and NADPH
C) to produce NADPH used in respiration
D) to convert light energy to the chemical energy of PGAL
E) to use ATP to make glucose
Answer:
The correct answer will be option-B.
Explanation:
Photosynthesis occurs in two stages: light-dependent and light-independent reaction. The light-dependent reaction is the reaction which takes place in the sunlight and converts light energy to chemical energy.
The reaction stores chemical energy in the form of energy equivalents mainly ATP through chemiosmosis and NADPH. These molecules are used in the second phase of the photosynthesis that is light-independent reactions where glucose is synthesized.
Thus, Option-B is the correct answer.
Option B is the correct answer. The primary function of light reaction in photosynthesis to produce ATP and NADPH.
Photosynthesis:
The light reaction form Energy rich molecules like NADPH and ATP using Light energy.These molecules used in the Calvin Cycle to produce Glucose.From above discussion we can say that Option A, C, D and E can be eliminated.
Hence we can say that the primary function of light reaction in photosynthesis to produce ATP and NADPH.
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How many membranes does the mitochondria have?
a. 1
b. 2
c. 3
d. 4
Answer:
b. 2
Explanation:
The mitochondria has 2 membranes namely the outer membrane and the inner membrane , which are separated by an inter membrane space. The outer membrane is selectively permeable to ions and molecules and also holds the whole mitochondria structure .in contrast ,the inner membrane is less permeable and it is where electron transport occurs , between protein complexes found within the structure.
How does the body monitor its core temperature?
A. Nerve cells in the skin feed the information to the hypothalamus.
B. The pituitary gland in the brain tracks the temperature of the blood.
C. Nerve cells monitor the temperature of the hypothalamus.
D. Core blood temperature alters the speed of the chemical reactions in the pituitary gland.
E. Core blood temperature alters the speed of nerve cells in the hypothalamus.
Answer: A. Nerve cells in the skin feed the information to the hypothalamus.
Explanation:
The hypothalamus is a part of the brain which controls the body temperature. The nerve cells present on the skin sends the signals to the hypothalamus when the body experience warm external temperature, which sends the signals to the sweat glands so that it's secretion makes the body cool. When the body feels cold then the hypothalamus sends the signal to the muscles to produce shivering to keep the body warm.
In which areas of the body would you expect to find the most Merkel discs and tactile corpuscles? Why?
Merkel discs and tactile corpuscles are found in the hairless skin layers like in lips and finger tips among the body parts.
Explanation:
Merkel cells was first discovered by Friedrich Merkel in 1875 and hence the cells were named after him. They are found in the epidermal layer of the cell.
They are found in the layer of the skin which helps in transmitting tactile signals. There are various types of tactile mechanoreceptors that work together during the process of touch. The Markel cells are encapsulated when touched.
Merkel discs and tactile corpuscles, types of mechanoreceptors found in the skin, are most commonly found in areas with high tactile sensitivity like the fingertips, lips, and genital areas. These areas generally require higher density of these receptors for tasks that demand detailed tactile feedback.
Explanation:Merkel discs and tactile corpuscles are types of mechanoreceptors found in the skin. These play a crucial role in the sense of touch and help us detect pressure, vibration, and texture.
The areas of the body where you would expect to find the most Merkel discs and tactile corpuscles are those that have a high degree of tactile sensitivity, such as the fingertips, the lips, and the genital areas. These areas require a greater density of Merkel discs and tactile corpuscles to provide the precision required for tasks that demand detailed tactile feedback.
The fingertips, hands, and face (especially the lips) are primary locations for these sensory receptors because our hands and face are often used to explore our environment and require fine tactile discrimination. The genital areas also have a high concentration of these receptors due to their role in sexual response.
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Agrobacterium infects plants and causes them to form tumors. You are asked to determine how long a plant must be exposed to these bacteria to become infected. Which of the following experiments will provide the best data to address that question?
(A) Measure the number of tumors formed on a plant when exposed to various concentrations of Agrobacterium.
(B) Measure the number of tumors formed on plants, which are exposed to Agrobacterium for different lengths of time.
(C) Determine the survival rate of Agrobacterium when exposed to different concentrations of an antibiotic.
(D) Measure the concentration of Agrobacterium in different soil environments where the plants grow.
Answer:
(B) Measure the number of tumors formed on plants, which are exposed to Agrobacterium for different lengths of time.
Explanation:
The problem question should be something like:
how long a plant must be exposed to these bacteria to become infected?
so the experimental design needs to include a time variable. The other answers do not include this variable.
Which action could produce a carbonyl group?
a. the replacement of the —OH of a carboxyl group with hydrogen
b. the addition of a thiol to a hydroxyl
c. the addition of a hydroxyl to a phosphate
d. the replacement of the nitrogen of an amine with oxygen
Answer:
a. the replacement of the —OH of a carboxyl group with hydrogen
Explanation:
By reduction methods a compound with a carboxylic acid group can be reduced. By adding H2 to said carboxylic group, some catalyst will be needed to allow this reaction to progress (in some cases metal palladium is usually used as a catalyst)
Before replacing the OH group, it is usually reacted to form an acyl chloride, which, when it is reduced with H2 and the catalyst is transformed into an acyl chloride and then rapidly reduced to form the carbonyl group and therefore the aldehyde
Replacing the -OH of a carboxyl group with hydrogen will produce a carbonyl group. Carbonyl groups consist of a carbon atom double bonded to an oxygen atom.
Explanation:The correct action that could produce a carbonyl group is the replacement of the —OH of a carboxyl group with hydrogen. The carbonyl group consists of a carbon atom double bonded to an oxygen atom. When the —OH of a carboxyl group is replaced with a hydrogen, the remaining carbon-oxygen double bond forms a carbonyl group, represented by the formula —C=O. An important aspect to remember is that carbonyl groups are common in aldehydes and ketones.
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Do the food crops we eat today look identical to the way they used to look and naturally grow? Why or why not?
a. Yes, because we haven't changed anything about our food crops
b. No, because GMOs have changed how all plants look and grow
c. No, because we select for certain traits that are favorable in food
d. Yes because whenever we genetically alter something, it can mutate back to the way it was before
Answer:
b. No, because GMOs have changed how all plants look and grow
Explanation:
A transgenic plant is a plant in which its genome has been modified by genetic engineering, to introduce one or several new genes, or to modify the function of a gene that is already inside the plant. As a consequence of this modification, the gene is transmitted to the offspring as a normal plant gene
The process of a transgenic plant has two important stages: transformation, which is when the gene is inserted into the genome of a plant cell that we want to change; and regeneration, which is when we already obtain a different plant from the transformed plant cell
The genes used help in obtaining new substances, changing the shape and time of plant development and also giving them the way to defend themselves against the elements that attack or damage normal plants. It is assumed that the transgenic plants were created to solve the problems that producers face due to pests, sudden climatic changes, lack of nutrients in the fields, diseases, etc., now with the transgenic at hand, we obtain better quality products, resistant or tolerant to all these factors that stalk them and even giving them greater performance.
Final answer:
Correct option is c. No, because we select for certain traits that are favorable in food. The food crops we eat today differ vastly from their wild ancestors due to thousands of years of human-led selective breeding and genetic modification, including both traditional breeding techniques and modern GMO technologies, to produce crops with desirable traits.
Explanation:
The food crops we eat today do not look identical to how they naturally grew in the wild due to human intervention through selective breeding and genetic modification. This process began thousands of years ago and involves selecting plants with desirable traits to breed, leading to significant changes in their genetic makeup over generations. This has resulted in the wide variety of crop species we have today that are better suited to human consumption, including changes in size, taste, and nutritional content. An example is maize, which was developed from a wild plant called teosinte in Southern Mexico through selective breeding, fundamentally altering its genetic instructions and appearance.
While GMOs (Genetically Modified Organisms) represent a more modern aspect of genetic manipulation, involving the direct editing of a plant's DNA to achieve desired traits such as disease resistance or increased yield, the history of crop modification is much older. Both traditional breeding and genetic engineering have played crucial roles in the development of the crops we consume, enhancing food security and reducing the environmental impact of agriculture. Therefore, the correct answer to the question is 'No, because we select for certain traits that are favorable in food'.
A normal cell in an adult woman has?
a. one functional X chromosome
b. two functional X chromosome
c. one functional Y chromosome
d. one X chromosome and one Y chromosome
e. three or more X chromosomes
Answer:
The correct answer will be option-A.
Explanation:
The females carry two X-chromosomes in their cells but one of these X-chromosome gets permanently inactivated during embryonic development.
The X-inactivation is known as lyonization which ensures that only one functional X-chromosome should be present like in males. This process is a random process and therefore a female can have both the functional X-chromosomes and males can also have a functional X-chromosome.
Thus, option-A is the correct answer.
Adipose tissues belong to ___________
a. nervous tissues
b. muscle tissues
c. connective tissues
d. epithelial tissues
Answer:
c. connective tissues
Explanation:
Adipose tissue is a connective tissue which is composed of cells called adipocytes. Since it a loose connective tissue located beneath the skin and around internal organs.
The main function of this tissue is to store fat, although it also cushions and insulates the body. It provides protective covering around internal organs. Since it stores fat it also functions as a reserve of nutrients.
Adipose tissue also acts as an endocrine organ. It has the ability to make a number of biologically active compounds that regulate metabolic homeostasis.
Hemoglobin buffers the pH of the cytosol of RBC by combining with ______ions.
Answer:
H+
Explanation:
Hemoglobin is the major protein of red blood cells. It has many exposed amino groups and carboxylic groups at its surface. These NH3 and COOH groups serve as weak acids and bases respectively and allow hemoglobin to serve as a buffer to maintain the pH of the RBC cytoplasm.
As the exposed amino groups of hemoglobin protein bind to the H+ ions, the free H+ concentration of the cytoplasm of RBC is reduced leading to a buffer action to maintain the pH.
You extract DNA from some of your cells and cut out the complete human growth hormone gene directly from this DNA. You put this gene into a plasmid and transform E.coli with the plasmid. To your dismay, you find that E. coli does not make any human growth hormone. What is the most likely explanation for the failure of this experiment?
A) Bacteria cannot carry out RNA splicing to remove introns and so produced a much larger protein.
B) Bacteria lack a nucleus for proper transcription of eukaryotic genes.
C) Human DNA cannot be cloned in a bacterium.
D) Human DNA can be maintained in cloned form only for brief periods in bacteria.
Answer:
A) Bacteria cannot carry out RNA splicing to remove introns and so produced a much larger protein.
Explanation:
Human is a eukaryote and has both introns and exons in its genes. Transcription of human genes forms a primary transcript that undergoes post-transcriptional modification.
One of the important even during the post-transcriptional modification is the removal of introns and joining the exons together to make a mature mRNA which in turn serves as the template for protein synthesis.
E. coli is a prokaryote and does not have the enzymatic machinery required for the splicing of introns.
Cloning of a complete human gene into the E. coli cells would not form the respective human protein since the bacterial cells would not be able to splice the introns from the primary transcript.
This pathogen is the leading cause of hospital-acquired infections and can be difficult to treat:
A) Clostridia.
B) Shigella.
C) Anthrax.
D) Pseudomonas.
Answer:
D) Pseudomonas
Explanation:
Pseudomonas is the group of gram negative bacteria which are considered opportunistic pathogens. This means that they infect in presence of an already existing ailment like cystic fibrosis. They usually target immuno compromised people.
Normally they are present on soil, water and skin. They are a major cause of hospital acquired infections like sepsis syndrome and ventilator-associated pneumonia. They thrive in moist conditions hence can be found on medical equipment causing cross infections in hospitals. They are resistant to many antibiotics hence the treatment is difficult.
A short piece of DNA or RNA onto which DNA polymerase begins to add nucleotides
a. Leading strand
b. Okazaki fragment
c. primer
d. clamp-loading complex
Answer:
Primer
Explanation:
DNA polymerase can't start adding nucleotides without having something to "hold on" to. This is why it needs a small fragment of DNA or RNA that binds the DNA template where it needs to be copied. Without this primer, DNA polymerase doesn't work.
Answer:
c. primer
Explanation:
DNA polymerases are enzymes that carry out DNA replication. This enzyme cannot initiate the synthesis of the new chain, therefore, a short fragment of RNA that is called a primer must be created and must be matched to the chain that will be used as a template. Thus, the DNA polymerase enzyme begins to add nucleotides from the first one extending the 3 'end of the existing chain.
Cyclic electron flow in the chloroplast produces
A) ATP
B) NADPH.
C) glucose
D) A and B.
E) A, B, and C
Final answer:
Cyclic electron flow in the chloroplast produces ATP by utilizing a created proton gradient, and it does not directly produce NADPH or glucose.
Explanation:
Cyclic electron flow in the chloroplast is involved in the light-dependent reactions of photosynthesis. During this process, electrons are transferred in a cycle within the chloroplast and this flow is used to create a proton gradient across the thylakoid membrane. This proton gradient is then utilized by the ATP synthase enzyme to produce ATP. Cyclic electron flow does not produce NADPH or glucose directly; NADPH is typically produced in the non-cyclic flow where electrons eventually reduce NADP+ to NADPH. Glucose is synthesized during the light-independent reactions, also known as the Calvin cycle, which uses ATP and NADPH produced by the light-dependent reactions.
This process occurs during the light reactions of photosynthesis. Cyclic electron flow generates ATP by creating a proton gradient across the thylakoid membrane. It also produces NADPH, which is used in the Calvin cycle to convert carbon dioxide into glucose.
Gene conversion of Neurospora requires recombination and which of the following events?
a. reversion
b. suppression
c. photoreactivation
d. heteroduplex formation
e. inversion
Answer: d. heteroduplex formation
Explanation:
A heteroduplex is a double stranded molecule of the nucleic acid that is originated by the recombination of the only single complementary strand that can be derived from different sources, that is from the different homologous chromosomes or can develop from different organisms.
Thus hetroduplex formation is the gene conversion event that requires recombination.
Answer:
d
Explanation:A heteroduplex is a double-stranded (duplex) molecule of nucleic acid originated through the genetic recombination of single complementary strands derived from different sources, such as from different homologous chromosomes or even from different organisms.
The Triassic/Jurassic extinction paved the way for non-avian dinosaurs to become the dominant vertebrates for the rest of the Mesozoic. However, there were many other vertebrates around at this time Which of these is a possible reason that non-avian dinosaurs were so successful?
a. The late Devonian extinction left many ecological niches open for non-avian dinosaurs to fill
b. Non-avian dinosaurs produce eggs with hard shells which provides protection against desiccation
c. Non-avian dinosaurs were al small and so didn' t require much vegetation to survive
d. The possession of feathers by both major clades of non-avian dinosaurs allowed them to survive the swings in temperature seen through the Mesozoic
e. The evolution of a bi-directional tidal breathing respiratory mechanism allowed them to outcompete other groups of vertebrates.
Answer:
d. The possession of feathers by both major clades of non-avian dinosaurs allowed them to survive the swings in temperature seen through the Mesozoic
Explanation:
The possession of feathers provided dinosaurs with a major advantage: mesothermy. This kind of metabolism is a transition form between cold- (ectothermy) and warm-blooded (endotherm), increasing their adaptation capabilities as the climate changed. The Mesozoic saw the breaking up of Pangaea first into two landmasses (Laurasia and Gondwana) and more individual landmasses towards the end.
a. The late Devonian extinction left many ecological niches open for non-avian dinosaurs to fill.
This cannot be the right answer since the Devonian extinction did not occur during the Mesozoic. The Permo-Triassic extinction did open many ecological niches, but these were exploited by all ornithodirans (meaning crocodiles, dinosaurs, and pterosaurs).
b. Non-avian dinosaurs produce eggs with hard shells which provides protection against desiccation
This is an advantage that relates to the success of amniotes (all vertebrates except for amphibians), and it played an important role in vertebrate evolution during the Late Devonian.
c. Non-avian dinosaurs were al small and so didn' t require much vegetation to survive.
Dinosaurs occupied several size scales, from very small to the most gigantic forms. Additionally, not all of them were herbivores. Although herbivory evolved independently in dinosaurs at least three times (Sauropodomorpha, Thyreophora, Neornithischia), the first dinosaurs were carnivores.
e. The evolution of a bi-directional tidal breathing respiratory mechanism allowed them to outcompete other groups of vertebrates.
This respiratory mechanism evolved at the beginnings of reptile evolution (as early as the Pensylvannian in the Carboniferous). It consists of having two influxes (exhalation and inhalation) of air into the lungs through the same channel. Fish, for instance, have an unidirectional breathing respiratory mechanism were the water enters through the mouth and leaves through the gills, were the oxygen is filtered. Dinosaurs already inherited this breathing mechanism.
In the moss Polytrichum commune, the haploid chromosome number is 7. A haploid male gamete fuses with a haploid female gamete to form a diploid cell that divides and develops into the multicellular sporophyte. Cells of the sporophyte then undergo meiosis to produce haploid cells called spores. What is the probability that an individual spore will contain a set of chromosomes all of which came from the male gamete? Assume no recombination.
Answer:
1/128
Explanation:
In a diploid individual, 2ⁿ possible gametes can be produced, where n is the haploid chromosome number.
From those possible gametes,
[tex](\frac{1}{2})^n[/tex] is the number of gametes that will contain maternal chromosomes only[tex](\frac{1}{2})^n[/tex] is the number of gametes that will contain paternal chromosomes only [tex]1-2(\frac{1}{2})^n[/tex] is the number of gametes that will contain a combination of both maternal and paternal chromosomes.The probability that an individual spore will contain a set of chromosomes all of which came from the male gamete will be:
[tex](\frac{1}{2})^7=\frac{1}{128}[/tex]Final answer:
The probability that an individual spore of Polytrichum commune will contain chromosomes solely from the male gamete is 1/128 or about 0.78%.
Explanation:
In the life cycle of the moss Polytrichum commune, with a haploid chromosome number of 7, the probability that an individual spore will contain a set of chromosomes all of which came from the male gamete is 1/128 or about 0.78%. This is because during fertilization, a haploid male gamete fuses with a haploid female gamete to form a diploid zygote. The zygote then develops into a sporophyte, which is a diploid multicellular organism. This sporophyte will then produce haploid spores through meiosis. Assuming no recombination, the spores will each receive a random assortment of chromosomes from the two sets present in the diploid cells. Since meiosis involves the random segregation of each pair of homologous chromosomes, the probability for each chromosome to come from the male gamete is 1/2. Given there are 7 chromosomes, we calculate this probability as (1/2)⁷ which equals 1/128.
Which of the following steps has not yet been accomplished by scientists studying the origin of life?
a. synthesis of small RNA polymers by ribozymes
b. formation of molecular aggregates with selectively permeable membranes
c. formation of protocells that use DNA to direct the polymerization of amino acids
d. abiotic synthesis of organic molecules
Answer:
The correct answer is option c. "formation of protocells that use DNA to direct the polymerization of amino acids".
Explanation:
The polymerization of amino acids is a complex biological function that involves multiple proteins and cofactors working together at different locations in the cell. Even though there are some scientific advances in the production of synthetic protocells (cell like structures made from synthetic particles), the formation of protocells able to synthesize amino acids from DNA directly has not been accomplished.
Which of the following statements correctly describes any chemical reaction that has reached equilibrium?
a. the concentration of products and reactants are equal.
b. The reaction is now irreversible.
c. Both forward and reverse reactions have halted.
d. The rates of the forward and reverse reactions are equal.
Answer:
Option (d).
Explanation:
Equilibrium may be defined as the state of the equality on both the sides of the reaction. Different types of equilibrium are physical equilibrium, chemical equilibrium and dynamic equilibrium.
Chemical equilibrium may be defined as the equilibrium in which the reactants and products concentration remains constant with time. The rate of the backward reaction is equal to the rate of forward reaction.
Thus, the correct answer is option (d).
The statement that correctly describes a chemical reaction at equilibrium is that the rates of the forward and reverse reactions are equal. This means that the reactions are still taking place, but there is no net change in the concentrations of the reactants or products. The equilibrium does not imply that the concentrations of reactants and products are equal, or that the reaction is irreversible.
Explanation:The statement that correctly describes any chemical reaction that has reached equilibrium is: 'The rates of the forward and reverse reactions are equal. When a chemical reaction is at equilibrium, it does not mean that the concentrations of the products and reactants are equal (Option A), or that the forward and reverse reactions have halted (Option C). Instead, the forward and reverse reactions continue to take place, but at equal rates, meaning there is no net change in the amounts of the reactants or products. Lastly, reaching equilibrium does not make a reaction irreversible (Option B). A reaction at equilibrium can be disturbed, and the system can shift to either make more reactants or products in response.
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A genetic carrier is someone who
a. has a defective allele and defective phenotype
b. has a defective allele and normal phenotype
c. has one copy of a defective dominant allele
d. has one copy of a defective allele
Answer:
The correct answer is option B. has a defective allele and normal phenotype.
Explanation:
Genetic carrier or the hereditary carrier is an organism or a person that has a recessive allele for a particular trait or character (generally mutation) but does not exhibit the trait or any character related to the trait.
The carriers are normal in the sex-linked characters in comparison to the autosomal traits. Females are generally the carrier for sex-linked characters and carry the allele to the next generation.
Thus, the correct answer is option B. has a defective allele and normal.
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
a. oxidation of glucose and other organic compounds.
b. flow of electrons down the electron transport chain.
c. H+ concentration gradient across the membrane holding ATP synthase.
d. transfer of phosphate to ADP.
Answer: The correct answer is option c.
Explanation:
ATP synthase is an enzyme present in inner mitochondrial membrane which catalyses the formation of ATP.
It gets energy directly from chemiosmosis, that is, diffusion of protons from inter-membrane space into mitochondrial matrix through ATP synthase.
The flow of electrons down the electron transport chain help in building the proton concentration gradient across the inner mitochondrial membrane.
The proton then diffuse down the concentration gradient provides the ATP synthase with energy required for synthesis of ATP.
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the:
c. H+ concentration gradient across the membrane holding ATP synthase.During the ATP synthase, there is a movement of the enzyme which is responsible for the synthesis which forms the adenosine triphosphate.
As a result of this, energy is released from the chemiosmosis which moves the protons from where they are plentiful, to where they are needed .
This causes the H+ concentration gradient to move across the gradient which holds the ATP synthase.
Therefore, the correct answer is option C.
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The function of ANP is antagonistic to the renin-angiotensin-aldosterone-system.
a. True
b. False
Answer:
A. True
Explanation:
The renin-angiotensin-aldosterone system stabilizes blood pressure and volume. The system constricts arteries and increases the amount of blood that the heart pumps, as well as the reabsorption of sodium (Na+) by the nephrons. Also, it decreases the glomerular filtration rate. All this increases blood volume and pressure.
On the other hand, ANP decreases blood volume and pressure by increasing the glomerular filtration rate and decreasing reabsorption of sodium by nephrons. Finally, this hormone inhibits the release of renin, aldosterone, and ADH.
The female external genitalia are collectively called the vulva.
a. True
b. False
The correct answer is A. True
Explanation:
The external genitalia or vulva includes different organs and structures such as the inner lips, the mons pubis, the urinary meatus, among others that are external rather than internal as it occurs in the case of the uterus, the cervix or the ovaries. All of these structures are linked mainly to reproduction or the urinary system in the case of the urinary meatus. There, it is true the female external genitalia is collectively called the vulva as all the organs and structures in this zone are commonly known by this name.
The term refers to the collective external female genitalia, including the labia majora and minora, , and the openings of the urethra and. Therefore, the answer to the question is true.
Explanation:The term is indeed used in biology and health to refer to the collective external female genitalia. This includes anatomical structures such as the labia majora (outer lips), labia minora (inner lips), and the openings of the urethra . So in answer to the question, the female external genitalia are collectively called the , we can confidently affirm that this is true.
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Which amino acid would most likely be attached to a tRNA with the anti-codon 5'-UGA-3'?
a. Gin
b. Leu
c. Ser
d. None of the above
Answer:
None of the above.
Explanation:
t RNA (transfer RNA) contains the anticodon that are complimentary to the codon of the mRNA molecule. These codons codes for the particular amino acid by the process of translation.
The tRNA contains the anti-codon UGA. The UGA anti-codon is a stop codon and does not code for any amino acid. The UGA codon acts as the signal for the termination of the translation process.
Thus, the correct answer is option (d).
Studying the same group of individuals from age 2 to age 40 is an example of which of the following research methods?
a. Cross-Sectional
b. Longitudinal
c. Archival
d. None Of The Above
Answer:
a. Cross sectional
Explanation:
Longitudinal research is a method in with data is recollected repeatedly over a period of time from the same subjects. Archival method is gathering information from archival records. Cross-sectional studies analyze data from a population at a specific period of time, this population can be integrated by people with different characteristics (in this case, age) but with another characteristics in common, for example, ethnicity, gender, etc)
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