Answer:
C. Troublesome weather patterns is one of the current factors affecting extraction of resources from the rainforest.
The human stress system evolved to deal with events such as getting chased by a lion. Which modern stress activates the stress system in the same way as getting chased by a lion?
Final answer:
Modern stressors like public speaking or deadlines trigger the fight or flight response similar to ancestral threats like being chased by a lion. This chronic activation of the stress system can lead to serious health issues.
Explanation:
The modern stress that activates the stress system in the same way as getting chased by a lion would be psychological threats, such as public speaking or facing a looming deadline. These modern stressors activate the fight or flight response, which the human nervous system has evolved over millions of years to handle immediate physical threats. The autonomic nervous system triggers a series of hormonal and physiological adjustments when faced with such stress. Unfortunately, modern stressors tend to be prolonged and can lead to chronic activation of this system, which can have serious health consequences, including cardiovascular disease, diabetes, anxiety disorders, depression, and impaired judgment.
The following data were obtained from pour plates used to test the effectiveness of a food preservative. Two samples of cottage cheese were inoculated with bacteria; the preservative was added to one sample. After incubation, samples of the cottage cheese (control) and samples treated with the preservative (experimental) were diluted and plated on nutrient agar. Calculate the number of bacteria. Was the preservative effective
Answer:
The colony-forming unit includes the fungal or the bacterial cells and can be used for the cell counting. The colony forming unit is used for the viable cells.
The cfu/ ml can be calculated as follows:
cfu/ml=(no. of colonies × dilution factor)/volume of culture plate
In control:
We have given, the no. of colonies=160
, dilution factor=400 and volume=1ml
The cfu of the control is
cfu/ml(control)=(160 × 400)/1=64000 cfu/ml
For the experimental data,
We have given the no. of colonies=32
, dilution factor=200 and volume=0.1 ml
.
cfu/ml=32 × 200/0.1=64000 cfu/ml
.
Since, the cfu of the control and the experiment is equal, the preservative is of no use.
To determine the effectiveness of a food preservative, the number of bacteria can be calculated by counting the colonies on the pour plates. By comparing the number of colonies in the control and experimental samples, the effectiveness of the preservative can be determined.
Explanation:The number of bacteria can be calculated by counting the number of colonies on the pour plates. The control sample represents the growth of bacteria without the preservative, while the experimental sample represents the growth of bacteria with the preservative. By comparing the number of colonies in each sample, you can determine the effectiveness of the preservative. If the experimental sample has significantly fewer colonies than the control sample, it suggests that the preservative is effective in inhibiting bacterial growth.
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Maureen does not seem to take responsibility for her actions (e.g., always creating excuses for coming home past curfew and acting like a victim of teachers when it comes to bad grades). In order for her to take responsibility for her behavior, she needs to become more ____________.A. situation-conscious.
B. self-conscious.
C. self-possessed.
D. condent.
Final answer:
Maureen should become more self-conscious (B), aware of her actions and their consequences, and develop an internal locus of control to take responsibility for her behavior, enhancing her conscientiousness.
Explanation:
In order for Maureen to take responsibility for her behavior, she needs to become more self-conscious. This means she should be more aware of her own actions and their impact, as well as develop an ability to reflect on her behavior. For example, instead of blaming others for her bad grades, like Jane with an external locus of control, Maureen could develop an internal locus of control where she recognizes her role in her academic performance. Developing conscientiousness is also key, as it involves being punctual, following rules, working hard, and being decisive—all traits that support taking personal responsibility.
Do butterflies remember life as a caterpillar?
Answer: Yes
Explanation: They have vivid memories of the cold nights even
Answer:
Yes
Explanation:
Select the best description of the negative selection process of lymphocyte maturation.
A) teaching a lymphocyte to recognize "self" from foreign antigens
B) removal of lymphocytes that react with "self" cells
C) removal of lymphocytes that fail to recognize "self" cells
D) allowing the survival of lymphocytes that cannot bind to MHC proteins
Answer:
B) removal of lymphocytes that react with "self" cells
Explanation:
By negative selection, we mean to say that the lymphocytes which are reacting with self cells too strongly must undergo apoptosis otherwise they will cause auto-immunity which will lead to destruction of self cells.
Before negative selection, the naive lymphocytes undergo positive selection during which they are allowed to interact with MHC-I or MHC-II. This kind of selection is necessary so as to ensure that the selected lymphocytes have affinity towards MHC molecule for generation of effective immune response whenever it is required. All those cells that do not recognize self antigen undergo apoptosis because they are useless and the lymphocytes which recognize MHC moderately are selected for the next stage which is negative selection.
Once these lymphocytes have passed test for positive selection, they have to undergo test for negative selection. All those lymphocytes which are interacting very strongly with self antigen are rejected and finally undergo apoptosis.
Negative selection in lymphocyte maturation refers to the removal of lymphocytes that react with the body's own cells to prevent potential auto-immune diseases.
Explanation:The best description of the negative selection process of lymphocyte maturation is B) removal of lymphocytes that react with "self" cells.
During maturation, lymphocytes undergo a process whereby those that recognise and therefore would react to "self" antigens, are eliminated. This is a crucial part of immune system development because if these "self-reacting" cells were allowed to remain, they could potentially attack the body's own cells, leading to auto-immune diseases.
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What are the small channels which connect osteocytes within an osteon?
Answer:
Haversian canals
Explanation:
Osteoblasts are the cells which form a mature bone and the osteocyte cells which helps in the resorption and deposition in the cell. The osteocytes are also involved in calcium removal and help remove the skeletal deformations.
The outer side of the bone is connected with each the blood vessels and the nerves through which osteocytes are also connected is known as the Haversian canals. The Haversian canals are the tubes which are microscopic present in the bone.
Thus, Haversian canals are correct.
Answer: Haversian canals
Explanation:
The haversian canals are the microscopic tubules or tunnels in the cortical bone of the nerve fibers that have few capillaries. These canals helps to provide the oxygen and nutrition to the bones. The haversian canals forms a channel within the osteon or bone cells which keeps the bone cell together.
These haversian canals helps in communication within the cells that occur through connections called as canaliculi.
ANSWER 4 QUICK QUESTIONS!!
What accomplishment are you most proud of? ...
Which of your friends are you proudest of? ...
What's the most beautiful place you've ever been? ...
Do you feel like a leader or a follower? ...
Answer:
Quick?
Explanation:
My garden.
My best friend.
the mountains.
Follower.
Answer:
I am proud of washing the dishes
My friend I'm most proudest of is James, because he washed the dishes
The most beautiful place I've been to is the sink.
I feel like a leader because I wash the dishes
Explanation:
Although the mechanisms by which aerobic training leads to enhanced aerobic performance in adolescents are still unclear, it is likely that ________________ may play a role.
Answer:
increased maximal stroke volume
Explanation:
Stroke volume is the amount of blood put out by the left ventricle during a contraction. By doing the regular aerobic training one can increase its maximal stroke volume. More the stroke volume of a person less will be its heart rate because more amount of blood will be pumped by the heart in a single time.
This is the reason why athletes have a decreased heart rate than normal people. So till now the mechanism of enhanced aerobic performance lead by aerobic training is not clear but it can be said that increased maximal stroke volume may play a role.
What are the disadvantages of a flatworms digestive system having
The provided question is incomplete, however the complete question is as follows:
What are the disadvantages of a flatworm's digestive system having only one opening?
Answer:
The correct answer is - cannot consume food continuously .
Explanation:
The main disadvantage of digestive system in the flatworm are one way of opening which is a characteristic feature of many Platyhelminthes phylum organism. This type of digestive system where food enters and exits with the same and only opening available.
In flatworms, once the organism take the food it has to wait for the food to be digested and excreted out by the same opening it use to eat and leave the same opening.
Thus, the correct answer is - cannot consume food continuously.
The question is incomplete. The complete question is as follows:
What are the disadvantages of a flatworm's digestive system having only one opening?
Answer:
The digestive system of the flatworms has been modified depending on their host parasite interaction. They have simple digestive system with the single opening.
This digestive system might have some disadvantages as the food consumption is not continuous due to the single opening. The ingestion and excretion as same opening and this increases the timing of the digestion and excretion process. The energy is expanded more in this type of the digestive system.
What activity does bipedalism in primates describe? Group of answer choices walking on two feet walking on four feet walking using two legs and a tail swinging from branch to branch
Bipedalism in primates is described as walking on two feet.
Explanation:
Bipedalism refers to the ability of walking on two feet. This is an evolutionary adaptation that has developed in many higher animals and has enabled them to reside and survive in diverse habitat. Though bipedalism is possible in all primates but it is generally not followed by them except in human beings.
Answer:
walking on two feet
Explanation:
took the quiz
Cells grown in laboratory culture dishes undergo only a fixed number of division before dying. The number of possible divisions drops depending on the age of the donor organism. This phenomenon is called the
Answer:
Hayflick limit
Explanation:
The Hayflick limit, or Hayflick phenomenon, is the number of times a normal human cell population will divide before cell division stops. It was postulated by Leonard Hayflick in 1961,
Which type of epithelium lines the inferior portions of the pharynx?
Answer:
The type of epithelium that lines the inferior portions of the pharynx is stratified squamous epithelium.
Explanation:
The pharynx is a structure made up of muscles and mucous membranes -like many internal organs- that is part of the respiratory system and is an intermediate step in the digestive tract.
This structure has two portions:
Upper or nasopharynx Lower, or oropharynx, in contact with the airways.Some even propose that the borderline surface between the pharynx and larynx can be called the laryngopharynx, due to its tissue structure.
The lower portion of the pharynx is covered by a squamous stratified epithelium, the inner layers of which rest on a basal lamina. The more superficial layers provide protection to the interior of the pharynx against friction, in addition to remaining lubricated by mucous secretion at that level.
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A microbial ecologist wants to study a bacterium that is adapted to growth in lake water containing very low nutrient concentrations. Assuming that a suitable growth medium is available for this organism, which type of culture would be best to use for growing this organism in the lab?
A) this organism cannot be grown in the lab.
B) a batch culture using a low-nutrient medium
C) on Petri plates containing a low-nutrient medium
D) a chemostat using a low-nutrient medium
Explanation:
The continuous procedure was single-arrange chemostat development without distribution, henceforth the procedure is persistently taken care of with the development medium and the way of life stock is pulled back at a similar rate so as to keep up the bioreactor volume steadyChemostats have for some time been another supported stage for exploratory advancement, and were, truth be told, developed for this application. A chemostat is a development vessel into which a crisp medium is conveyed at a steady rate and cells and spent medium flood at that equivalent rate. In this way, the way of life is compelled to gap to stay aware of the weakening, and the framework exists in a steady-state where information sources coordinate yieldsHence, the right answer is option D "a chemostat using a low-nutrient medium"Overactive sebaceous glands can cause:________a) fine hairs on the forehead to become brittle. b) the forehead's skin to become dry. c) bacteria on the forehead's skin to grow and multiply freely. d) seborrhea, a disease characterized by red, itchy lesions on the scalp.
Answer:
d) seborrhea, a disease characterized by red, itchy lesions on the scalp.
Explanation:
Sebaceous gland are the glands which are usually present beneath the skin and with the hair follicles. They are also known as oil-producing glands as they released sebum.
If the sebaceous gland becomes too active and secrete extra sebum than it can cause a condition called Seborrhoea. In Seborrhoea microbe like Malassezia fungi species colonizes the area where sebum is produced and initiates local inflammatory response which causes scaly patches, itchy lesions, and red skin. So the correct answer is d.
Overactive sebaceous glands primarily cause seborrhea, which is characterized by red, itchy lesions on the scalp. The glands produce excessive sebum resulting in this condition, while options a, b, and c are not direct consequences of overactive sebaceous glands.
Explanation:Overactive sebaceous glands in the skin can lead to various outcomes, but the most corresponding answer to this question is option d) seborrhea, a disease characterized by red, itchy lesions on the scalp. The sebaceous glands produce an oily substance called sebum, which plays a critical role in the protection and nourishment of skin. However, when these glands become overactive, they generate excessive amounts of sebum. This excess sebum can result in a condition known as seborrhea, displaying symptoms of redness, itchiness, and flaky skin particularly on the scalp. Options a, b, and c are not direct effects of overactive sebaceous glands.
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After teaching a class about the endocrine system, the instructor determines that the students need additional instruction when they identify which of the following as an endocrine gland?
A)
Pancreas
B)
Adrenal gland
C)
Testes
D)
Kidneys
Answer:
The correct answer is D) Kidneys
Explanation:
The endocrine system contains the glands which secrete their secretion called hormone directly in the blood because their target organs are situated distantly from them where the hormone reach through blood.
Pancreas, adrenal gland, and testes are the endocrine glands which secrete hormones directly in the blood. The kidney is not an endocrine gland and does not secrete any hormone. The kidney is responsible for filtering blood and removal of nitrogenous and other waste from the body. Therefore the correct answer is D.
Why are we more vigilant about zoonotic diseases for the gametogenesis lab?
Let's add the missing piece of information:
In this part of the lab we'll be taking some reasonable precautions to make sure that we don't allow undue contact between cat/dog parasites and the interior of our bodies.
Why are we more vigilant about zoonotic diseases for the Gametogenesis lab?
[Please remember to wash your hands!]
- The samples are fresh (they were very recently a part of a living organism.)
- The samples are from warm-blooded animals which have similar diseases to ours
- The samples are from mammals, so their parasites are closer evolved to us
- We are using sharp tools and razor blades, making access into our bloodstream potentially easier
All answers indicates the need for necessary precautions in the course of the experiment.
Explanation:
A zoonosis (plural zoonoses, or zoonotic diseases) is an infectious disease which originated from bacteria, viruses, or parasites that moves from non-human animals (mainly vertebrates) to humans. Major contemporary diseases like Ebola virus disease and salmonellosis are zoonoses.
Zoonoses have varying forms of transmission. In direct zoonosis the disease is mainly transmitted from other animals to humans via media e.g. air (influenza) or via bites and saliva (rabies).
Transmission could also be through an intermediate species (known as a vector), that serve as host for the disease pathogen as it is not affected by the diseases presence.
The need to be vigilant in the course of the lab experiment to avoid infection and transmission from one Hunan to another.
Answer:
Diseases which are spread from animals( higher animals )other than man to human being are called zoonosis. They are caused by bacteria, viruses, fungi and parasites in theses animals, and through bites, domestication, droplets contacts, farming, and hunting are passed to human. Some are also transmitted as vectors.
Statistically, they represented 61% of thousands of pathogens known to have infected human.
Answers.
Therefore during process of Gametogeneis and other experiemntal procedures in the laboratory, a lot of vigilance is needed because,
→In most cases to guarantee the experimental success, they are needed fresh to be used in the laboratory, thus careful measures not to have contact with the possible infected fluid and blood of these animals is needed.
→Human shared the almost same physiological make up with these animals, thus it is easy for human to also serve as host for the same pathogens that they harbour, thus during lab.preparations necessary protection to guide against these should be taken
→Experimental procedures may involved laceration, and which involved blood spillage and contacts.Therefore necessary measures is needed to avoid unnecessary cuts which may lead to infections transmission and possible contamination.
Explanation:
D
When sperm and egg cells undergo meiosis, the number of chromosomes goes from ______ to _______. When an egg is fertilized by a sperm cell that number goes from ______ to ______. 2 to 2; 1 to 1 1 to 1; 2 to 2 1 to 2; 2 to 1 2 to 1; 1 to 2
Final answer:
The number of chromosomes in sperm and egg cells goes from diploid (46) to haploid (23) during meiosis. Upon fertilization, these haploid cells merge to form a diploid zygote with 46 chromosomes. The correct sequence is 2 to 1; 1 to 2.
Explanation:
When sperm and egg cells undergo meiosis, the number of chromosomes goes from diploid (2n) to haploid (n). Specifically, the number goes from 46 to 23 chromosomes in humans. When an egg is fertilized by a sperm cell, this number goes from haploid to diploid, or from n to 2n, effectively from 23 to 46 chromosomes. Therefore, the correct sequence of numbers from the options provided is 2 to 1; 1 to 2.
During this process, DNA is copied once, and then the cell divides twice, leading to gametes with half as much genetic information as the original cell. Upon fertilization, the gametes unite and the original number of chromosomes is restored in the zygote, which now contains the full complement of genetic information necessary for the development of a new organism.
A concept that there is a specific time in an organism's development during which external factors have a unique and irreversible impact is:
A. ethology
B. equifinality
C. critical period
D. zone of proximal development
Answer:
C. Critical period.
Explanation:
Critical period:
In developmental biology, ciritical period is also known as sensitive period which is defined as a period or stage of maturation in the organism's lifespan in which nervous system is more sensitive to various environmental stimulus. Means, brain cell connections are more receptive to influence from surrounding environmental factors. Our body's many cruical functions including behavior are established during critical period with irreversible impact.
The half-life of Carbon-14 is 5730 years. Suppose a fossil is found with 50% of Carbon-14 as compared to a living sample. How old is the fossil?
Answer:
5732 years
Explanation:
Radioactive decay can be determined by using the equation:
[tex]N_t = N_0e^{- \lambda t}[/tex]
where;
[tex]N_t[/tex] = number of decayed atoms at time (t)
[tex]N_0[/tex] = initial number of decayed atoms
[tex]\lambda[/tex] = decay constant
So, if we equate the natural log of the above; we have:
[tex]In(N_t) = In(N_0)-\lambda t[/tex]
[tex]\frac{In(N_t)} { In(N_0)}} = -\lambda t[/tex]
where;
[tex]\lambda[/tex] = [tex]\frac{0.693}{t_{1/2}}[/tex]
[tex]\lambda[/tex] = [tex]\frac{0.693}{5730}[/tex]
[tex]\lambda[/tex] = [tex]1.209*10^{-4[/tex]
[tex]In(\frac{50}{100}) =-(1.209 *10^{-4})*t[/tex]
[tex]-0.693 = -(1.209*10^{-4})*t[/tex]
[tex]t= \frac{0.693}{1.209*10^{-4}}[/tex]
t = 5732.01 years
t = 5732 years.
Hence, the fossil is 5732 years old.
Answer: 5730 years
Explanation:
Because it takes 5730 years for half of a sample of carbon-14 atoms to decay. It says that 50% of the carbon atoms have decayed so that means that 5730 years have elapsed for that fossil.
What are expenditures for assets subsequent to acquisition?
The expenditures for assets subsequent to acquisition are purchase price, incidental expenses and installation charges.
What is expenditure?Expenditure is defined as the entire energy cost of maintaining steady bodily conditions plus the energy cost of physical activities.
It can also be defined as a measurement of the increased energy metabolism required to perform a function.
There are four basic component of expenditure
Resting metabolic rate The thermic effect of foodThe thermic effect of energyAdaptive or facultative or thermogenesisThus, the expenditures for assets subsequent to acquisition are purchase price, incidental expenses and installation charges.
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What cellular components are responsible for small molecule transport within the cytoplasm?
A.
flagella
B.
mitochondria
C.
proteins
D.
chromosomes
E.
vesicles
Reset
Why is scarcity the basis of all economic decisions? Describe how the role of the government in a society influences the three economic questions. (Site 1)
Answer:
Scarcity is the basis of all economic decision because it will not go away. No matter what there will always be scarcity. It is impossible for the government to provide everything for their people. There are costs for every economic choice the government makes. There is a limit on what we need to produce product whether it is time, money or effort. The government decides the budget of something to be produce. They decide how to make things a certain way. And they choose the how the resources are beneficial to the environment. Scarcity will always be here so we have to learn to make decisions with it.
Explanation:
I put this on edge and got it right
Scarcity is the basis of all economic decision because it will not go away. No matter what there will always be scarcity.
What is the impossible task of the government?It is impossible for the government to provide everything for their people. There are costs for every economic choice the government makes. There is a limit on what we need to produce product whether it is time, money or effort. The government decides the budget of something to be produce. They decide how to make things a certain way.
They choose the how the resources are beneficial to the environment. Scarcity will always be here so we have to learn to make decisions with it. Goods and services are produced through natural resources, which are mostly scarce. In this way, economic theory aims to rationalize the production and distribution of these goods and services to satisfy the demands of society.
Therefore, Scarcity is the basis of all economic decision because it will not go away. No matter what there will always be scarcity.
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A grasshopper jumps along a line. His first jump takes him 1 cm., the second 2 cm, etc. Each jump can take him to the right or to the left. Prove that after 2017 jumps, the grasshopper cannot be in the same location it started.
Answer:
The grasshopper cannot be in the same location it started because by 2017, it would have covered a distance of 1017576.5 to either left or right. and that distance is not an integer.
Explanation:
The grasshopper jumps in integer of 1 cm to either right or left
Calculating for the total distance covered in 2017 jumps
Total Distance = (2017 x 2018)/2 = 2035153 cm
To either right or left: this implies that the total distance be divided by 2
=> 1017576.5 cm
It shows that at some point, the grasshopper will not be in a position of integer on either right or left.
Therefore, it can not get to its initial point of start.
To prove that after 2017 jumps the grasshopper cannot be in the same location it started, we can calculate the total distance covered by the grasshopper. By using the formula for the sum of an arithmetic series, we find that the grasshopper would have covered a total distance of 2036171 cm after 2017 jumps. Therefore, the grasshopper cannot be in the same location it started.
Explanation:To prove that after 2017 jumps the grasshopper cannot be in the same location it started, we need to consider the distance covered by each jump. The grasshopper jumps 1 cm in the first jump, 2 cm in the second, and so on. We can observe that the distance covered in each jump is increasing by 1 cm. Therefore, after 2017 jumps, the grasshopper would have covered a total distance of 1 + 2 + 3 + ... + 2017 cm.
To find this total distance, we can use the formula for the sum of an arithmetic series: S_n = (n/2) * (a_1 + a_n), where S_n is the sum of the first n terms, a_1 is the first term, and a_n is the nth term. In this case, n = 2017, a_1 = 1, and a_n = 2017.
Substituting these values into the formula, we get S_n = (2017/2) * (1 + 2017) = 2017/2 * 2018 = 2036171 cm.
Based on this calculation, we can conclude that after 2017 jumps, the grasshopper would have covered a total distance of 2036171 cm. Since this distance is greater than zero, it is impossible for the grasshopper to be in the same location it started.
In a winter of an epidemic flu, 2000 babies were surveyed by a well-known pharmaceutical company to determine if the company's new medicine was effective after two days. Among 120 babies who had the flu and were given the medicine, 29 were cured within two days. Among 280 babies who had the flu but were not given the medicine, 56 were cured within two days. Is there any significant indication that supports the company's claim of the effectiveness of the medicine?
Final answer:
A preliminary comparison of cure rates indicates a slight advantage for the medicated group over the non-medicated group, but statistical analysis is required to determine significance. The medicine's goal is to manage symptoms, as complete prevention is not typically achievable with current antivirals like oseltamivir.
Explanation:
To assess the effectiveness of the pharmaceutical company's new flu medicine, we can compare the cure rates between the group that received the medicine and the group that did not. In the medicated group, 29 out of 120 babies were cured within two days, giving us a cure rate of approximately 24.2%. In contrast, the non-medicated group saw 56 out of 280 babies cured, which translates to a cure rate of around 20%.
While there is a numerical difference between the cure rates of the two groups, to determine if this difference is statistically significant, a hypothesis test such as Chi-square or Fisher's exact test would usually be conducted. These tests would provide a p-value that, when compared against a chosen significance level (commonly 0.05), would indicate whether the observed difference in cure rates could be due to chance or if it is statistically significant. However, without further statistical analysis, we cannot make a definitive conclusion on the effectiveness of the medicine.
It is also important to note that antivirals like oseltamivir and other medications prescribed for flu symptoms work to reduce symptom duration and inhibit the spread of virus but are not curative. They are part of the recommended treatment protocols for managing flu symptoms along with prophylactic antimicrobials and over-the-counter drugs to alleviate fever and headache.
Which organs plays a role in water balance regulation?
Answer: The kidneys can regulate water levels in the body; they conserve water if you are dehydrated, and they can make urine more dilute to expel excess water if necessary.
In the example of adrenaline signaling used in the animation, suppose each amplification step produces hundredfold active molecules. How many total modified protein target molecules result from a single activated signal receptor? A. 300 B. 900 C. 10,000 D. 1,000,000 E. 100,000,000
Answer:
Option D. 1000000
Explanation:
Adrenaline signaling occurs when the the hormones clings to the cell surface of the Adrenaline receptor.
The total modified protein target molecules resulting from a single activated signal receptor is 1,000,000 and this results in the consumption of 100 molecules of Guanosine triphosphate (GTP) and 1,010,000 molecules of Adenosine triphosphate (ATP).
For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogenous base of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogenous bases. Thus, labeling the nitrogenous bases would provide a stronger signal than labeling the phosphates. Why won't this experiment work?
Answer:
Explanation:
The aim of the Hershey and Chase experiment was to show that DNA and not proteins are the genetic material.
Proteins are made up of amino acids which also has a nitrogenous base. Since the whole point of the experiment was to differentiate between the two i.e. show which one is the genetic material, it would be impossible to differentiate between DNA and proteins if the nitrogenous base was labelled.
A 60-year-old G4P4 woman presents with a two-year history of urine leakage with activity such as coughing, sneezing and lifting. Her past medical history is significant for vaginal deliveries of infants over 9 pounds. She had a previous abdominal hysterectomy and bilateral salpingo-oophorectomy for uterine fibroids. She is on vaginal estrogen for atrophic vaginitis. Physical exam shows no anterior, apical or posterior wall vaginal prolapse. Vagina is well-estrogenized. Post-void residual was normal. Q-tip test showed a straining angle of 60 degrees from the horizontal. Cough stress test showed leakage of urine synchronous with the cough. Cystometrogram revealed the absence of detrusor instability. The patient failed pelvic muscle exercises and was not interested in an incontinence pessary. Which of the following is the best surgical option for this patient?A. Retropubic urethropexyB. Needle suspensionC. Anterior repairD. Urethral bulking procedureE. Colpocleisis
Answer:
A. Retropubic urethropexy
Explanation:
Since it is stated that the woman has a two-year history of urine leakage and had a previous abdominal hysterectomy. These are indications of GSI i.e. Genuine Stress Incontinence, a condition in which increments of intra-abdominal pressure produce involuntary urine loss.
Both urethral hypermobility and Intrinsic Sphincteric Deficiency (ISD) are causes of stress urinary incontinence. Only Retropubic urethropexy is best for patients suffering from GSI due to both hypermobility and Intrinsic Sphincteric Deficiency (ISD). The other options can only address one or none of the specified causes.
Which of the following is the earliest step in transcription? A. RNA polymerase encounters a termination signal, and the DNA molecule is released. B. Complementary RNA nucleotides are synthesized and added to the mRNA molecule. C. Introns are excised from the pre-mRNA strand. D. RNA polymerase binds to the promoter on the template strand of DNA.
Answer:
D.
Explanation:
Transcription is the first step in gene expression. It involves duplicating a gene's DNA sequence to make an RNA molecule.
It is performed by enzymes called RNA polymerases, which link nucleotides to form an RNA strand (using a DNA strand as a template)
Answer: D. RNA polymerase binds to the promoter on the template strand of DNA.
Explanation: The first step in transcription is termed initiation step. In this step, the enzyme RNA polymerase binds to a region or section of a gene called the promoter. This specific action results to the signalling of the DNA to unwind so the enzyme can decode the bases in the DNA strands. The enzyme now make a strand of mRNA with contemporary bases.
Four of the five processes listed below will disrupt Hardy-Weinberg equilibrium. Select the exception. a. natural selection b. genetic drift c. punctuated equilibrium d. non-random mating e. migration
Answer:
B, C, D, and E
Explanation:
Hardy-Weinberg equilibrium is defined as the model that explains the relationship between phenotypic and genotypic frequencies relationship, using the five assumptions of:
No mutationNo migrationNo selectionRandom matingInfinite populationAnswer:
natural selection, genetic drift, non-random mating, and migration (option A, B, D, and E)
Explanation:
In the Hardy-Weinberg equilibrium principle, the frequencies of alleles and genotypes remain the same in a population, from generation to generation, with no net change in allele or genotype frequencies. This means, no evolutionary change is occurring in the population. However, for this principle to hold, the following conditions must be present, which are:
There must be random mating, that is every individual of the population has an equal chance of mating with any other member the population There must be no net mutation The population size must be large enough to reduce the probability of the allele frequencies to change by genetic drift caused by random fluctuations, as common in a small population size Absence of migration of individuals into the population or outside the population Absence of natural selection which can cause some phenotypes to be selected against othersTherefore, the 4 processes, out of the 5 processes listed, that can disrupt Hardy-Weinberg equilibrium in a population are natural selection, genetic drift, non-random mating, and migration (option A, B, D, and E)
A punctuated equilibrium would not, as the population is said to be stable or become stable over a long period of time with little evolutionary change in the course of life.