Answer:
d. secondary endosymbiosis.
Explanation:
When a living cell acquires another organism that eventually becomes a part of this cell, this process is known as primary endosymbiosis.When an organism that has already undergone primary endosymbiosis engulfs another eukaryotic organism then this process is known as secondary endosymbiosis. Secondary endosymbiosis has been known to occur in plastids because of which they are surrounded by two membranes. This bilayer is present because one of the layers is the original outer membrane of the organism and the other membrane is that of the organism that has been engulfed.Predict the change in leukocyte count in a patient suffering from leukemia (cancer involving leukocytes)
Answer:
Leukemia may be defined as the cancer of the blood cells especially white blood cells. The leukemia may occur due to mutation or may also occur due to the biological agents.
Leukemia causes the abnormal and uncontrolled growth of the blood cells. These white blood cells are unable to fight with infections and causes the bone marrow to produce impair formation of blood cells. The patient shows abnormal growth and large count of leukocytes.
What are the monomers of nucleic acids called?
a. amino acids
b. monosaccharides
c. carbon
d. nucleotides
Answer:
Nucleotides.
Explanation:
Two types of nucleic acids are DNA and RNA. DNA is present as the genetic material in all the living organisms except some viruses. RNA is present as genetic material in some viruses only.
DNA is made of the polymers of nucleotides. The nucleotides consists of the nitrogenous bases (adenine, guanine, thymine and cytosine), deoxyribose pentose sugar and phosphate group. The RNA consists of oxyribose sugar and uracil instead of thymine.
Thus, the correct answer is option (d).
In photosynthesis, ATP and electrons from light reactions are used in ___________
a. glycolysis
b. krebs cycle
c. oxidative phosphorylation
d. calvin cycle
Answer:
d. Calvin cycle
Explanation:
During the light reactions or photochemical reactions of photosynthesis, chlorophyll molecules absorb sunlight and convert light energy into assimilatory power in the form of the electron carrier molecule nicotinamide adenine dinucleotide phosphate (NADPH) and the ATP.
The ATP and NADPH used as a source of energy to fix or reduce carbon dioxide into glucose.
The reduction of carbon dioxide to glucose occurs in the stroma of the chloroplast. The reactions of the conversions are called the Calvin cycle.
The Suillus lakei mushroom is commonly found
growingaround the bas of conifers, especially the Douglas fir.
Offer apossible explanation of this association of a fungus and
plant.
Answer:
Suillus lakei mushroom refers to a mycorrhizal fungus, which grows in company with Douglas fir, and can be witnessed in the locations where this tree is found.
This association illustrates a symbiotic relationship, known as mycorrhizae, which is produced between the plant and the fungi. The fungi colonize the root system of the host plant, in this case, Douglas fir, and provide enhanced nutrient and water absorption tendencies, while the plant offers the fungus with carbohydrates produced from the process of photosynthesis.
The Suillus lakei mushroom's preference for growing around conifers, particularly the Douglas fir, can be a result of a mycorrhizal association. This symbiotic relationship allows the fungus to draw nutrients from the tree, while also offering benefits to the plant such as increased nutrient and water uptake.
Explanation:The Suillus lakei mushroom, commonly associated with conifers like the Douglas fir, is a perfect example of a symbiotic relationship known as mycorrhizal association. In this mutually beneficial relationship, the mushroom obtains nutrients from the tree's root system, particularly the sugars produced through photosynthesis.
In return, the fungus helps the tree by increasing its water and nutrient absorption capacity from the soil, as fungal mycelium forms a vast network that can reach sources of nutrients and water far beyond the tree roots' range. Thus, the mushroom's habitat preference can be driven by a combination of nutritional need and a unique ability to form productive symbiotic relationships with some specific trees like the Douglas fir.
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Cancer is often the result of activation of ________to ________ and the inactivation of _______ genes.
A) oncogenes, tumor-suppressor genes, proto-oncogenes
B) oncogenes, proto-oncogenes, tumor-suppressor genes
C) proto-oncogenes, oncogenes, tumor-suppressor genes
D) proto-suppressor genes, suppressors, oncogenes
Answer:
Option (C).
Explanation:
Cancer may be defined as the phenomena of the uncontrolled growth of the cell division and the cells require less nutrient medium to grow. Two main types of tumor are benign tumor and malignant tumor.
Proto- oncogenes generally regulates the growth and metabolism. The mutation may leads to the formation of proto-oncogenes to the oncogenes. These oncogenes are responsible for the formation of cancer. The main function of tumor suppressor gene is the suppressor inactivates the tumor genes. There suppression may result in the formation of tumor.
Thus, the correct answer is option (C).
Final answer:
Cancer development involves the mutation of proto-oncogenes into oncogenes, resulting in uncontrolled cell growth, and the inactivation of tumor-suppressor genes, which fail to put the necessary checks on this growth. The correct answer to the question is C) proto-oncogenes, oncogenes, tumor-suppressor genes.
Explanation:
Cancer is often the result of activation of proto-oncogenes to oncogenes and the inactivation of tumor-suppressor genes. Therefore, the correct answer is C) proto-oncogenes, oncogenes, tumor-suppressor genes.
Proto-oncogenes are genes that normally help cells grow. When these genes are mutated, they can become oncogenes, which may cause cells to grow out of control. Oncogenes can be thought of as a car's accelerator stuck in the 'on' position. On the other hand, tumor-suppressor genes are like the brakes of a car; when these genes are turned off or inactivated, cells can multiply uncontrollably because there's nothing to stop them.
In summary, cancer development can be compared to a failing car's cruise control, where there is an overactive accelerator (due to oncogenes) and malfunctioning brakes (due to inactivated tumor-suppressor genes).
pH can be regulated in the collecting duct.
a. True
b. False
Answer:
a. True
Explanation:
pH can be regulated by the collecting duct of the kidney. Collecting duct play an important role in the maintenance of pH and ionic balance of the blood by the selective secretion of hydrogen ions (protons) and potassium ions. Collecting duct is long duct which extends from the cortex of the kidney to the inner part of the medulla. In the collecting duct, a large amount of water reabsorption occurs.
Which of these occurs first?
a. Helicase unwinds DNA
b. Sliding clamp binds around DNA
c. DnaA binds at the origin of replication
d. DNA pol III copies DNA
Answer:
The correct answer is a. Helicase unwinds DNA
Explanation:
DNA replication is a process in which DNA make it's own copy. There are several enzymes and factors which access the DNA replication process like helicase, primase, SSB protein, DNA polymerase etc.
The first step in DNA replication is the unwinding of double stranded DNA which is accomplished by an enzyme called Helicase. Helicase opens up the double stranded DNA at replication fork by breaking the hydrogen bond between the nucleotides of complementary strands.
This provides a single stranded template for DNA polymerase to form a new complementary strand. In E. coli Dna B is the primary helicase and in humans the primary helicase is MCM( minichromosome maintenance protein complex).
How does a mutation in the RAS gene lead to uncontrolled cellular division?
A. The RAS protein becomes stuck in the "on" position.
B. The RAS protein can no longer act as a tumor suppressor.
C. The RAS protein becomes stuck in the "off" position.
D. The RAS protein gets stuck in the plasma membrane.
E. The RAS protein can no longer act to repair DNA damage.
Answer: I would think A but get a second opinion to be 100% sure, okay.
If the question were why can’t a mutated RAS gene stop uncontrolled cellular division/cancer I could easily answer the question. So if you also need that answered I could just saying.
The correct answer is A. The mutation in the RAS gene leads to uncontrolled cellular division because the RAS protein becomes stuck in the on position.
RAS genes encode for proteins that are involved in the transmission of signals within cells. These signals are critical for the regulation of cell division. Normally, RAS proteins function as molecular switches that cycle between an on state, where they are active and can transmit signals, and an off state, where they are inactive. This cycling is tightly regulated by the binding and hydrolysis of GTP (guanosine triphosphate) to GDP (guanosine diphosphate). When a mutation occurs in the RAS gene, the RAS protein can lose its ability to hydrolyze GTP to GDP, which means it can become stuck in the on position. As a result, the RAS protein continues to transmit signals for cell growth and division even in the absence of external growth factors. This leads to uncontrolled cellular proliferation, which is a hallmark of cancer. To clarify the other options: B. The RAS protein can no longer act as a tumor suppressor. - This option is incorrect because RAS is not a tumor suppressor; it is a proto-oncogene. When mutated, it can become an oncogene that promotes cancer. C. The RAS protein becomes stuck in the off position. - This option is incorrect because it is the on position that leads to continuous signaling for cell division. D. The RAS protein gets stuck in the plasma membrane. - While it is true that RAS proteins are located in the plasma membrane to function properly, simply being stuck in the membrane is not what leads to uncontrolled cell division. It is the inability to turn off the signal due to the mutation that causes the problem. E. The RAS protein can no longer act to repair DNA damage. - This option is incorrect because RAS is not directly involved in DNA repair. Its primary role is in signal transduction pathways that control cell growth and division.
After the DNA is unwound, what protein keeps the strands from reannealing?
a. DNA primase
b. Sliding clamp
c. Helicase
d. SSB protein
Answer:
SSB protein.
Explanation:
DNA replication may be defined as the process of formation of daughter RNA molecule from the template DNA. The process of DNA replication occur in 5' to 3' direction.
The DNA strand must be unwound to initiate the DNA replication. The DNA strands must not reanneal for the replication process. Single stranded binding protein (SSB) bounds to the DNA strands and prevent them from re anneal.
Thus, the correct answer is option (d).
The protein that keeps unwound DNA strands from reannealing is the single-strand DNA binding protein (SSB protein), not DNA primase, sliding clamp, or helicase. In eukaryotes, DNA is organized around histones.
Explanation:After the DNA is unwound during replication, the protein that keeps the DNA strands from reannealing is the single-strand DNA binding protein (SSB protein). These proteins bind to the separated strands of DNA, thereby ensuring that these strands remain single-stranded and accessible for the next steps in DNA replication. This prevents the DNA strands from spontaneously forming double-stranded DNA again.
In eukaryotes, DNA is wrapped around proteins called histones, not single-stranded binding proteins or sliding clamps. The attachment of DNA to histones helps in compacting the large eukaryotic genomes so that they fit within the cell nucleus, and also plays a role in the regulation of gene expression.
Which of the following statements is not true?
a. Archaea and bacteria have different membrane lipids.
b. The cell walls of archaea lack peptidoglycan.
c. Only bacteria have histones associated with DNA.
d. Only some archaea use CO2 to oxidize H2, releasing methane.
Answer:
c. False
This statement is incorrect because the DNA of bacteria is circular without histones.
Explanation:
a. True
Some archaea have very specific lipids in their membrane. Differently of the bacterias that have usual lipids in their membranes.
b. True
Archaebacteria do not have peptidoglycans in their cell wall
d. True
Methanogenic archaeobacteria are those that use carbon dioxide and hydrogen to produce methane. They are found in the digestive system of ruminants, sewers and swamps.
Final answer:
The incorrect statement is that only bacteria have histones associated with DNA because both archaea and eukaryotes have histones, highlighting a common misconception about cellular biology. Option c
Explanation:
The statement that is not true among the given options is c. Only bacteria have histones associated with DNA. This is because both archaea and eukaryotes have histones associated with their DNA, which is contrary to what the statement implies. Let's clarify the true statements:
Archaea and bacteria have different membrane lipids: Indeed, archaea have membrane lipids that are ether-linked with branches (phytanyl), whereas bacteria have ester-linked fatty acids.
The cell walls of archaea lack peptidoglycan: Correct, archaea typically do not have peptidoglycan in their cell walls, which is a major component in the cell walls of bacteria.
Only some archaea use CO₂ to oxidize H₂, releasing methane: True, this is a process known as methanogenesis and is specific to certain archaea known as methanogens.
Therefore, the myth about histones being exclusive to bacteria is debunked, showcasing that archaea share this characteristic with eukaryotes, not bacteria. Option c
In binomial nomenclature, the more general of the two names comes second.
a. True
b. False
Answer:
False
Explanation:
As one moves from species to kingdom in a taxonomic hierarchy, the categories become more general. This is due to the grouping of distantly related organisms in a higher category as compared to the evolutionary relationships between the organisms of a lower category.
In binomial nomenclature, the name of the genus is written first followed by the name of the species.
Since the genus is a "more general category" than a species, the more general category is mentioned first in binomial nomenclature.
For a gene suspected of causing hypertension in humans, you observe the following genotype frequencies: A1A1 0.574; A1A2 0.339; A2A2 0.087. Is this gene in Hardy-Weinberg equilibrium? Why or why not? (Assume that a difference of three percent or more in any of the observed versus expected frequencies is statistically significant.) See Section 23.1 (Page 458) .
Answer:
This gene is in Hardy-Weinberg equilibrium
Explanation:
As per the second equation of Hardy-Weinberg equilibrium, sum of genotypic frequencies of all types with in a population must be equal to one
Frequency for genotype A1A1 ([tex]p^{2}[/tex]) [tex]= 0.574[/tex]
Frequency for genotype A2A2 ([tex]q^{2}[/tex]) [tex]= 0.339[/tex]
Frequency for genotype A2A1 ([tex]2pq[/tex]) [tex]= 0.0.087[/tex]
Now,
[tex]p^2+q^2+2pq = 1\\[/tex]
Substituting the given values in above equation, we get -
[tex]0.574 + 0.339+0.087=1\\1=1[/tex]
Hence, this gene is in Hardy-Weinberg equilibrium
Which of the following statements describes characteristics of cancerous cells?
A. All cancer cells are the result of a bacterial infection.
B. Cancerous cells respond to normal checkpoints.
C. Cancer cells exhibit uncontrolled growth.
D. All cancer cells have the ability to metastasize.
E. All of these are true about cancerous cells.
The characteristic most commonly associated with cancerous cells is their ability to grow and divide in an uncontrolled manner. Not all cancers result from bacterial infections, cancerous cells usually ignore normal checkpoints, and not all have the ability to metastasize.
Explanation:The statement which best describes the characteristics of cancerous cells is: 'C. Cancer cells exhibit uncontrolled growth'. This is because cancer cells differ from normal cells in many ways. They are not subject to the control mechanisms that regulate cell growth and reproduction. Cancer cells continue to divide and grow in an unregulated manner, disregarding the normal checks and balances that control cell division.
Not all cancer cells result from a bacterial infection (A), so this statement is incorrect. Cancerous cells usually ignore the normal checkpoints (B) the body has in place, instead, propagating without control, so this statement is misleading. While some cancer cells have the ability to metastasize, i.e., spread to other parts of the body (D), not all of them do, making this statement inaccurate.
Thus, option E is also not correct since not all of these are true about cancerous cells.
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What is fever and explain why it is considered to be a nonspecific immune response?
Answer:
Body of an organisms have a range of the normal temperature that is maintained by the body by homeostasis. When the range of the body temperature rise above that range it it known as fever. The normal temperature of human body is normally 36-37 degree centigrade. Mild fever is not need any assistance to bring it back to normal range it is doe by the body to fight against infection or change takes place. Fever can be measured in mouth, rectum, and underarms.
It is considered as nonspecific response mechanism as it is take place due to different type of reasons and its affect or mechanisms is same for all, not specific as the cell mediated or antibody mediated responses of specific defense mechanism.
DNA has a charge associated with it. What functional group that carries a charge is included in DNA, and how do we use the charge to our advantage while doing gel electrophoresis? How does this relate to using the phrase "run to the red" while performing gel electrolysis?
Answer:
DNA is made up of sugar-phosphate backbone and the phosphate in the DNA contains the negative charge, therefore, DNA is a negatively charged molecule present in the nucleus.
This negative charge is very important in separating the DNA according to their charge and size during gel electrophoresis. During gel electrophoresis DNA of different size is run on an agarose gel in the presence of current and DNA fragments move toward positive charge due to negative in nature.
Small size DNA moves fast through the gel large size DNA moves slow towards negative pole, therefore, separating the DNA according to their size. In gel electrophoresis, red pole is positive pole and the black pole is negative so runs to the red phrase is signifying that the DNA is always run towards the red pole.
Name the three essential active site residues of chymotrypsin and describe how each is involved in the catalytic mechanism.
Answer:
The active site residues include Serine, Histidine and Aspartatic acid
Explanation:
The catalytic triad at the active site of Chymotrypsin includes Ser-105 (Serine), His-57 (Histidine) and Asp-102 (Aspartic acid).
His-57: Deprotonates and polarizes Ser-105 so that it is able to react with substrate.
Asp-102: The carboxyl group of Asp-102 hydrogen bonds with the R-group of the His-57 which facilitates the deprotonation of Ser-105.
Ser-105: The strong nucleophile of serine attacks the substrate leading to hydrolysis.
Which of the following processes is activated by insulin?
A. Triacylglycerol breakdown
B. Gluconeogenesis
C. Glycogenolysis
D. Fatty acid synthesis
E. Adenylate cyclase activity
Answer: Gluconeogenesis
Explanation:
Gluconeogenesis is a pathway that is used by the body to create glucose from the other molecules. It is an important pathway that allows the body to store energy for brain in the form of glucose.
This process is regulated by insulin, which helps in this process of storing energy. Insulin inhibits the secretion of glycogen which is a activator of gluconeogenesis.
This hormone helps in maintaining a significant amount of glucose in the blood and rest of the glucose is stored for the vital organs of the body.
The most important adaptive advantage associated with the filamentous nature of fungal mycelia is
a. the ability to form haustoria and parasitize other organisms.
b. the potential to inhabit almost all terrestrial habitats.
c. the increased chance of contact between mating types.
d. an extensive surface area well suited for invasive growth and absorptive nutrition.
Answer:
d. an extensive surface area well suited for invasive growth and absorptive nutrition.
Explanation:
Fungi have an extracellular nutrition. These means enzymes are released to environment to start degrading macromolecules which can be later be absorbed (absorptive nutrition) through cell membranes. Having multiple spots (bigger surface area) through which it can nurture speeds up the rate at which it can grow leading to a faster growth and higher competition over resources.
The filamentous nature of fungal mycelia provides a significant adaptive advantage due to its extensive surface area, which facilitates efficient invasive growth and absorptive nutrition.
Explanation:The most important adaptive advantage associated with the filamentous nature of fungal mycelia is d. an extensive surface area well suited for invasive growth and absorptive nutrition.
Fungal mycelia are composed of hyphae that branch and form a network, leading to a high surface-area-to-volume ratio. This structural feature enables fungi to efficiently absorb water and nutrients from their environment. They achieve this by secreting hydrolytic enzymes into their surroundings to digest large organic molecules into smaller ones that can be easily absorbed. While other options like forming haustoria, colonizing many habitats, and facilitating mating may be advantageous, the key to a fungus's survival lies in its ability to absorb nutrients effectively due to the extensive surface area of mycelium.
Which is considered to be a process by which electrons aregenerally
removed frombiomolecules catabolism or anabolism?
You must spell out the answercorrectly to receive credit.
Answer:
Catabolism
Explanation:
Catabolism refers to the metabolic pathways to break down the complex biomolecules into simpler substances and release the energy stored in their chemical bonds.
The catabolic reactions are oxidizing reactions and remove the electrons from the substances.
For example, cellular respiration is a catabolic pathway for glucose as it oxidizes glucose into CO2 and H2O. During aerobic cellular respiration, molecular oxygen serves as the terminal electron acceptor and is reduced into water.
During mRNA processing, what is put on the 3' end of a primary mRNA transcript?
a. a poly-A tail
b. a cap
c. an exon
d. an intron
Answer:
A poly-A tail.
Explanation:
Transcription may be defined as the process of formation of the RNA molecules from the DNA template. Eukaryotic RNA undergoes the process of mRNA processing.
The mRNA processing involves the post translation modification of RNA. The poly A (adenine) tail is added to the 3' end of the RNA transcript after the elongation. This poly A tail protects the RNA from the degradation and helps to export the RNA into the cytoplasm.
Thus, the correct answer is option (a).
Genetic variation in bacterial populations cannot result from
a.transduction c.mutation
b.conjugation d.meiosis.
Answer:
d. meiosis
Explanation:
Bacterial cells don't go through meiosis, it is unique to the eukaryotic cells.
Genetic variation in bacterial populations cannot result from meiosis, but it can occur through other mechanisms such as a. transduction, c. mutation, and b. conjugation.
Explanation:Genetic variation in bacterial populations cannot result from meiosis because meiosis is a process that only occurs in eukaryotic cells, not in prokaryotic bacteria. However, genetic variation in bacterial populations can occur through other mechanisms such as transduction, mutation, and also conjugation.
In addition to this, the process of transduction involves the transfer of genetic material between bacterial cells by viruses. Mutation is the spontaneous change in the DNA sequence, which can result in new genetic variations. Conjugation is a process where bacteria directly exchange genetic material, usually plasmids, with other bacteria.
The outer layer of a virus is called a capsid and is made of protein.
a. True
b. False
Answer:
a. True
Explanation:
Viruses are nor living nor non-living things. They do not metabolize, and only consist of nucleic acid in the inside of a protein cover which protects it. This proteinous layer is known with the term capsid, and is usually formed by units of certain proteins called capsomeres. Besides protection, these proteins serve as the structures that actually allows viruses contact and adhere to host cells during infection, that's why they are key components for the viruses success.
The largest unit within which gene flow can readily occur is a
a. population c. genus.
b. species d. hybrid.
Answer:
a. population
Explanation:
Gene flow cannot occur in hybrids because 99.9% of the time hybrids offspring are not fertile.
At genus level is not possible either because a hybrid is a cross breed at the genus level (horse-donkey).
A population is a group of species of 1 kind. A population of donkeys.
List three ways by which eukaryotes process mRNA after transcription.
Answer:
The post transcription modification include three ways i.e., capping, polyadenylation and splicing.
1. 5' Capping- mRNA capping is catalyzed by capping enzyme which is associated with RNA polymerase II. This enzyme adds the guanosin residue to 5' end of mRNA then methyl transferase adds methyl group to N⁷ position this guanine. Capping protects mRNA from degradation by enzymes presents in the cell.
2. Polyadenylation: In polyadenylation many adenosine residue is added at 3'end of mRNA by poly(A) polymerase. This poly A tail helps in exporting mRNA out of nucleus and binding of translational factors.
3. Splicing: In splicing process the non coding introns are removed from RNA so that only coding region i.e., exons are left in mRNA. It is important to remove unwanted sequence like introns which hinders in protein formation.
What causes a heart attack?
A. A blockage in the aorta
B. genetics
C. A blockage in the carotid arteries
D. A blockage in an artery in the brain
E. A blockage in an artery anywhere in the body
Answer: A. A blockage in the aorta
Explanation:
A heart attack happens when one or more aorta or coronary arteries get blocked. With the passage of time, the coronary artery becomes narrow that is because of the deposition of various substances such as fat, cholesterol and other reserves. This restricts the smooth circulation of blood hence results in heart attack or heart stroke.
A heart attack is usually caused by a blockage in a coronary artery due to atherosclerosis, with genetics and lifestyle factors influencing the risk.
Explanation:The cause of a heart attack, also known as myocardial infarction, is usually a blockage in a coronary artery, which supplies blood to the heart muscle. This blockage is often a result of atherosclerosis, a condition where cholesterol plaque builds up in the arteries and can rupture, forming a clot. This clot obstructs the flow of blood, depriving the heart muscle of oxygen and nutrients, leading to damage or death of the heart muscle cells. Genetics and lifestyle choices such as diet, exercise, and smoking can contribute to the risk of heart attack. A blockage in an artery in the brain or carotid artery can lead to a stroke, not a heart attack.
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Which sequence best describes the passage of sperm? 1. Seminiferous tubules. 2. Vas deference. 3. Epididymis 4. Ejaculatory duct 5. Urethra.
A. 3,1,2,4,5
B. 1,3,2,4,5
C. 5,4.2,3,1
D. 1,3,4,2,5
E. 3,1,4,2,5
Most animals with backbones, vertebrates, have a similar body plan: skull, ribs, two pairs of limbs, tail. What does this suggest about vertebrates?
A. Vertebrates are the best designed organisms.
B. Vertebrates all adapted to similar environmental conditions.
C. Vertebrates all have similar lifestyles.
D. Vertebrates have been around longer than most other organisms.
E. Vertebrates are all related to a common ancestor.
The correct answer is E. Vertebrates are all related to a common ancestor
Explanation:
According to biology and evolution, organisms from different species but that share similarities in morphology (body structures) as well as in genetics often have a phylogenetic relationship which means they descend from the same organism or share a common ancestor. This applies to multiple taxonomical levels including classes such as mammals or birds as it has been proved each of this derived from a common ancestor. Therefore, the similarity in the body structure (morphology) in all mammals suggest vertebrates are related to a common ancestor and as they evolved from this, they share similarities not only in terms of morphology but also in genetics.
Answer:
E
Explanation:
What is the difference between a disk-diffusion test and a kirby-Bauer test? Why is Mueller-hinton agar used in the kirby-bauer test?
Answer:
The Kirby-Bauer test and disk diffusion are the same.
Explanation:
Kirby-Bauer antibiotic disk diffusion is used for bacterial susceptibility testing. Mueller-hinton (MH) agar is used as it is the best medium for daily antibiotic testing as it supports growth of non-fastidious organisms. Furthermore, MH controls the rate of antibiotic diffusion through the agar.
Passive expiration is preceded by the:
a. recoil of the lungs
b. contraction of the internal intercostals muscles.
c. contraction of the diaphragm.
d. increase in atmospheric pressure.
e. increase in CO2 in the blood
Answer:
The correct answer is option a. "recoil of the lungs".
Explanation:
Normal respiration is passive, which means that no energy is needed to release the air from the lungs. Passive respiration is preceded by the recoil of the lungs that happens without any effort because of the elasticity of the lungs tissue. After inspiration, the diaphragm and intercostal muscles relax and the thoracic cavity and lungs decrease in volume. This causes that the interpulmonary pressure rises above atmospheric pressure, creating an air pressure gradient that put the air out of the lungs without the need of energy.
The seminiferous tubules
A. Are the site of spermatogenesis
B. Produce most of the seminal fluid.
C. Empty directly into the vas deferens
D. Are located within the cavernous body.
E. Receive fluid from the bulbourethral glands.
Answer:
The correct answer is option A. are the site of spermatogenesis.
Explanation:
The seminiferous tubules are present within the testes in males and the site of production, development, maturation of the sperm or spermatogenesis. In this reproductive organ, meiosis takes place to make sperm or male gametes.
The spermatogenesis is a three-stage process of producing mature spermatozoa from the stem cells or germ cells. The first phase is spermcytogenesis in which germ cell go under mitotic division followed by the second phase which is meiosis of the cell of the first phase and in the last phase is spermiogenesis.
Thus, the correct answer is option A. are the site of spermatogenesis.