Answer:
The battle against sexually transmitted illnesses, except for the relatively recent HIV/AIDS, has been one that has been present in humanity almost from its beginning. Infections caused by syphilis, ghonorrea, clamydia, among others, have been a part of humans since sexual activity has been around us. However, since the appearance of antibiotics, and other chemical agents to combat them, the scenario changes for mankind, as now, a diagnosis of such diseases was not basically a death sentence, or, a reason to be socially isolated. Another thing that changed, was the pattern and incidence of transmission, as now, with treatment, the pathogens could be stopped.
However, during the 19th century, with the appearance of medically more advanced technologies, better antibiotic treatments, and other public health measures, many of these STI´s, especially those that were most frequent, like syphilis, were no longer taken as certain death. However, it also became a reason for people to act more rashly and not think about transmission.
But in the 20th century, and especially since the appearance of the most deadly HIV virus, particularly in homosexual populations, things began to look bad for humans again. People died, and the only measure that could be taken as science learned about the pathogen, was isolation of those infected. Just as in the middle ages those infected with plague, were left aside, HIV-infected people became isolated. But during the 20th century, virology, the science that studies viruses and the possible treatments to it, and the adventure of DNA discoveries, led to a huge change. It was seen that there were a series of chemical components, that were able to completely detain, and in some cases eliminate, those viruses and bacteria that caused deadly STIs. But probably one of the biggest advances in the 20th century was the realization of the importance of education of people, campaigns to educate the people about contagion, ways of prevention and possible treatments.
In this question let's compare and contrast 19th century treatment for those living with an STD and 20th/21st century treatment for those living with HIV/AIDS.
STD in the 19th century and HIV 21st centurySyphilis came and stayed, spreading, especially in times of war. With modern medicine, the bacterium that causes the disease was identified in 1905. And five years later, the first effective treatment was discovered. But it was only in 1943, with the discovery of penicillin, that a cure for the disease was found.
Treatment for HIV infection is done through antiretroviral drugs that prevent the virus from multiplying in the body, helping to fight the disease and strengthen the immune system, despite not being able to eliminate the virus from the body.
With this information, we can conclude that we are able to interrupt this pattern in the USA, with the increase in specificity in the treatment for these diseases and information, more and more these diseases ended up.
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Historically, an important strategy for disrupting the adhesion of integrins to their ligands is by using a synthetic peptide that mimics the binding site on the ECM molecule to which the integrin attaches. In the case of fibronectin, the amino acid sequence is arginine-glycine-aspartate (when written using the single letter designation for each amino acid, this sequence becomes RGD). Explain why addition of such synthetic peptides would disrupt binding of cells to their normal substratum.
Answer:
Upon binding of integrins with such synthetic peptides, disrupts the receptors, and make them unavailable to bind with fibronectin or laminin.
It would impact in inhibition of binding of cells to extracellular matrix (ECM). It is an important strategy that disrupts the adhesion of integrins and ligands. It can have significant role in tumor invasion and metastasis.
Explain Gynecomastia in males.
Gynecomastia is an increase in the size of the mammary gland in men. The condition can occur in one or both breasts. It starts as a small mass under the nipple, which can be sensitive. One breast can be bigger than the other. Its cause is an imbalance between the stimulatory effects of estrogen (female sex hormones) and the inhibitory effects of androgens (male sex hormones) in the breast tissue, when the first ones increase, or the second ones descend.
Gynecomastia is a problem relatively common in the population, and there are three prevalence peaks throughout life:
Newborns: Between 60 and 90% of newborns have gynecomastia, produced by the passage of maternal estrogens through the placenta. It is a transient gynecomastia that disappears in about 2-3 weeks.
Puberty: Gynecomastia in puberty affects mainly young people aged between 10 and 14 years, and is due to the transient and physiological increase in estrogen that occurs at this age.
Elderly: Is due to an increase in fatty tissue with a greater peripheral aromatization ( a process that occurs in adipose tissue and that involves the conversion of androgens into estrogens), a decrease in the production of testosterone by the testes and the use of drugs.
David Fee studies sound waves so deep and low that humans cannot hear them. What are these low frequencies
called?
infrared
seismology
geosound
infrasound
Answer: infrasound
Explanation:
The infrasound is called as the low frequency sound. The frequency of these sounds is less than 20 Hz. The sound waves of the infrasound cannot be perceived by the humans as human ear are less sensitive to the low frequency. The infrasound can be produced in extreme weather conditions, earthquakes, meteor impacts, explosive detonation, collision of oceanic waves, waves on beach, and sound produced by the air conditioner.
Characteristics of the mature sperm include the ________. A. presence of two X chromosomes in approximately half the sperm B. absence of coiled mitochondria C. presence of Y chromosomes in approximately half the sperm D. absence of an acrosome
Answer:
Presence of Y chromosomes in approximately half the sperm.
Explanation:
Mature sperm cell consists of the following parts :
A head
A neck
A middle piece and
A tail.
Plasma membrane surrounds the complete body of sperm cell. Sperm head contains very little cytoplasm, an elongated haploid nucleus, the anterior portion of which is covered by a cap like structure called acrosome. The acrosome contains enzyme which help in the process of fertilization with ovum. Acrosome is derived from golgi apparatus. There is a short neck region which contains both the proximal and distal centriole. Proximal centriole plays an vital role in the first cleavage of zygote formed. Distal centriole gives rise to the the axial filament present in the long tail of sperm cell. The middle piece contains the mitochondria which are arranged spirally and produce energy for the movement of tail. The tail contains the central axial filament, small amount of cytoplasm and is surrounded by cell membrane as external sheath. The sperms cell swims at the rate of 1.5 to 3 mm per minute and reach the fertilization site within 30 minutes.
27. What is the major reactant needed for the Citric Acid Cycle (aka Krebs Cycle)?
a. Pyruvate
c. Chlorophyll A
b. Acetyl Co-A
D. Water
Answer: b. Acetyl Co-A
Explanation:
Acetyl CoA produced through pyruvate, amino acids, and fatty acids are oxidized in the Krebs cycle in CO2, obtaining as products NADH, FADH2 and GTP (ATP). Parallel to this oxidation, the Krebs cycle produces compounds used as precursors for biosynthesis. As it is a cycle, an oxaloacetate molecule could, in principle, oxidize an amount indefinite of acetyl CoA. Acetyl-CoA is formed from the oxidative decarboxylation of pyruvate, sequentially performed by pyruvate dehydrogenase -PDH (complex multi enzymatic of 3 enzymes), in the mitochondrial matrix.
True or False: A person may be considered overweight but not obese.
Answer:
The answer to the question: A person may be considered overweight but not obese, is, true.
Explanation:
The diagnosis of obesity, vs overweight depends entirely on the BMI, the body mass index. This measure depends on the relation between a person´s weight, height and age, and it establishes the amount of body fat the person has. If the ratio found is between 25 and 29.9, in the BMI, then the person is considered overweight, but not obese. However, if the person´s BMI is 30, or above, then the person is declared obese. This is why the answer is true.
The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge?
A cross bridge in biological terms refers to the connection formed between actin and myosin during muscle contraction. Once the muscle fiber sarcolemma is excited, it leads to the myosin heads linking with actin, causing muscle contraction. This process is known as the cross bridge cycle.
Explanation:A cross bridge refers to the connection formed between the myosin heads of the thick muscle fibers and actin sites of the thin muscle fibers during the process of muscle contraction. This process is called the cross bridge cycle.
When the sarcolemma, the cell membrane of a muscle fiber, is stimulated or excited, it triggers a chain reaction resulting in the myosin heads 'reaching out' and forming a link or 'bridge' with the actin. This pulling action of the myosin heads shortens the muscle fiber, resulting in muscle contraction. Following this, the myosin heads release, the fiber relaxes and the cross bridges are 'uncoupled' until the next excitation event.
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The excitement of the sarcolemma triggers a crucial step in muscle contraction known as the cross-bridge cycle.
A cross bridge is fundamentally the transient connection that occurs between the myosin heads, which are located on the muscle's thick filaments, and the binding sites on actin, which makes up the muscle's thin filaments. The hydrolysis of ATP powers this interaction, which modifies the configuration of the myosin heads. The actin filaments slide over the myosin filaments as the cycle continues, shortening the sarcomere and leading to muscular contraction. The cross bridge goes through several stages during the cycle, including attachment, power stroke, and detachment. The intricate cross-bridge cycle demonstrates how muscle function is supported by a carefully choreographed molecular dance.
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Curare, a poison extracted from South America shrub, blocks the binding of Each by muscle cells. What do you suppose would happen to your muscles, including the ones involved in breathing, if a toxic dose of curare entered your bloodstream?
Answer:
Curare if entered to the bloodstream can cause a lot of damages. Muscle paralysis could occur because of the blocking of acetylcholine (a neurotransmitter) and abnormal muscle's relaxation.
The respiratory muscles upon relaxation also cause respiratory paralysis that is extremely fatal and could cause death.
Curare is a poison that blocks acetylcholine release, causing loss of muscle activity, muscle relaxation, and eventual paralysis. If it enters the bloodstream, it could lead to a life-threatening situation as it could paralyze muscles involved in breathing, causing respiratory arrest.
Explanation:Curare is a toxin that functions by blocking the release of acetylcholine, a neurotransmitter that sends signals from neurons to muscle cells, inducing contraction. If a toxic dose of curare, such as that found in a South American shrub, entered your bloodstream, the resulting effect would most likely be a loss of muscle activity, progressing to muscle relaxation and then paralysis.
In muscle paralysis, your muscles would become incapable of contracting, which includes the muscles involved in breathing. As such a person could face serious consequences, including respiratory arrest, which can be life-threatening.
This is due to the role acetylcholine plays in the neuromuscular junction. When acetylcholine is prevented from binding with the muscle cells, the normal sequence of nerve signal transmission and muscle contraction is disrupted, leading to paralysis effect. Similarly, other neurotoxins such as Botulinum toxin (BONT) and Tetanus toxin have comparable effects but through slightly different mechanisms.
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The site of most absorption of nutrients is the
a. stomach.
b. small intestine.
c. large intestine
d. all of the above
Answer: b. small intestine.
Explanation:
The small intestine is approximately 4.5 meters long in a living person but is 6 meters long at autopsy when the muscles relax. Digestion occurs primarily in the duodenum, which receives the pancreatic juice enzymes. The small intestine provides a large surface area for absorption. Glucose and amino acids from food are absorbed through the small intestine and enter the blood via the hepatic portal vein, going to the liver.
2. The Isthmus of Panama cut off gene flow between Atlantic and Pacific populations of a species of fish. The cessation of gene flow led to the accumulation of genetic differences between the populations, which led to reproductive isolation. Now Atlantic and Pacific populations of this fish are separate species that cannot interbreed, even if they were again to come into contact with each other. The process described is that of
a. sympatric speciation.
b. parapatric speciation.
c. allopatric speciation.
d. reinforcement.
e. temporal isolation.
Answer:
C Allopatric Speciation
Explanation:
Evolution of two populations of same species into two separate species due to geographical isolation is called allopatric speciation.
In the given example, Isthmus of Panama serves as a geographical barrier and do not allow the interbreeding between Atlantic and Pacific fish populations of the same species.
These populations evolve genetic adaptation to make themselves better suited to the prevailing surroundings. Accumulation of genetic variations over generation leads to their reproductive isolation. Now, these two fish populations serve as two separate species as they can not interbreed.
Match the following terms to their definitions. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer. Words can be used more than once. ResetHelp Messenger RNA Ribosomal RNA Synthetase enzymes Transfer RNA ATP 1. : Forms part of the subunits for the protein synthesizing organelle. 2. : A molecule that binds to a specific codon and specific amino acid simultaneously. 3. : Attaches the correct amino acid to its transfer RNA. 4. : Provides the energy needed for synthesis reactions. 5. : Produced in the nucleus, this molecule specifies the exact sequence of amino acids of the protein to be made. 6. : May be attached to the ER or scattered in the cytoplasm.
Answer:
1. Forms part of the subunits for the protein-synthesizing organelle. - Ribosomal RNA.
2. A molecule that binds to a specific codon and specific amino acid simultaneously. - Transfer RNA.
3. Attaches the correct amino acid to its transfer RNA. - Synthetase enzymes.
4. It provides the energy needed for synthesis reactions. - ATP
5. Produced in the nucleus, this molecule specifies the exact sequence of amino acids of the protein to be made. - Messenger RNA
6. May be attached to the ER or scattered in the cytoplasm. - Ribosomal RNA.
Important notes:
- Messenger RNA is also written as mRNA
- Transfer RNA is also written as tRNA
- About point number 6:
To be more accurate, it is the whole ribosome that can be attached to the ER or scattered in the cytoplasm. However, because the ribosome is made of proteins and Ribosomal RNA, then it is also true that Ribosomal RNA can be attached to the ER or scattered in the cytoplasm. Although "synthetase enzymes" could be another option for this point, it is not accurate to say that synthetase enzymes, in general, could be attached to the ER or scattered in the cytoplasm because there are other synthetase enzymes in other places besides the cytoplasm or the Endoplasmatic Reticulum (ER).
The definitions are:
Ribosomal RNA: Forms part of the subunits for the protein synthesizing organelle.Transfer RNA: A molecule that binds to a specific codon and specific amino acid simultaneously.Synthetase enzymes: Attaches the correct amino acid to its transfer RNA.ATP: Provides the energy needed for synthesis reactions.Messenger RNA: Produced in the nucleus, this molecule specifies the exact sequence of amino acids of the protein to be made.Ribosomal RNA: May be attached to the ER or scattered in the cytoplasm.How to match the termsRibosomal RNA (rRNA): Ribosomal RNA forms part of the subunits of ribosomes, which are the protein synthesizing organelles in cells. Ribosomes consist of a combination of rRNA and proteins and play a crucial role in protein synthesis.
Transfer RNA (tRNA): Transfer RNA is a molecule that binds to a specific codon (a sequence of three nucleotides) on messenger RNA (mRNA) and carries a specific amino acid.
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In fruit flies, gray bodies (G) are dominant over black bodies (g), and red eyes (R) are dominant over orange eyes (r). Each individual possesses two alleles for each trait. If a fly that is homozygous dominant for both traits is crossed with a fly that is homozygous recessive for both traits, what is the predicted genotype of the offspring?
Answer:
The predicted genotype of the offspring is GgRr.
Explanation:
The gray body is dominant over black body. The genotype of gray body is GG and the genotype of black body is gg. Red eyes are dominant over orange eyes. The genotype for red eye is RR whereas the genotype of orange eye is rr.
GGRR is crossed with ggrr, the offspring produced by this cross is GgRr with gray body and red eyes.
GGRR × ggrr
GgRr.
In a cross between a homozygous dominant fruit fly and a homozygous recessive fruit fly, all offspring will have the heterozygous genotype GgRr. For X-linked traits, such as eye color in fruit flies, offspring ratios differ and are specific to whether the male or female expresses the recessive trait. These genetic principles also apply to human genetics.
Predicted Genotype of Offspring in a Fruit Fly Cross When a fruit fly that is homozygous dominant for both gray body and red eye traits (GGRR) is crossed with a fly that is homozygous recessive for both traits (ggrr), all the offspring will inherit one dominant and one recessive allele for each trait. Therefore, the predicted genotype of the offspring will be heterozygous for both traits (GgRr). This outcome is due to simple Mendelian inheritance, where each parent contributes one allele for each trait to their offspring. In the case of X-linked eye color traits, when a white-eyed male (XwY) is crossed with a female that is heterozygous for red eye color (XWXw), the offspring's eye color ratios can be predicted. The male offspring will have either red (XWY) or white (XwY) eyes, depending on whether they inherit the X chromosome carrying the dominant or recessive allele. The female offspring will all have red eyes since they will get the dominant XW allele from the mother and can only inherit the Y chromosome from the father. These principles are not only applicable in studying fruit fly genetics but also have implications in understanding human genetics, especially for X-linked conditions such as color blindness, hemophilia, and muscular dystrophy.
What is the action of the biceps femoris?
Answer:
The main action of biceps femoris is the knee flexion and hip extension.
Explanation:
Biceps femoris muscle is a thigh muscle present in the posterior part of the body. This muscle has two heads of origin.
Biceps femoris is involved in the knee flexion. The kknee flexion decreses the angle between the femur and tibia. Biceps femoris is also involved in the hip extension. The hip joints are open during hip extension.
The biceps femoris is a key muscle in the posterior thigh compartment, responsible for flexing the knee, extending the hip, and also participates in the abduction and lateral rotation of the thigh.
Explanation:Action of the Biceps Femoris
The biceps femoris is a key muscle within the posterior compartment of the thigh, which is a part of what is commonly known as the hamstrings. It plays a crucial role in the movement of both the hip and the knee joints. The action of the biceps femoris is to flex the leg at the knee and to also assist in hip extension. Additionally, this versatile muscle is involved in abducting (moving away from the midline of the body) and laterally rotating the thigh at the hip joint, which allows for movements such as sitting cross-legged.
When the knee bends, the biceps femoris is the agonist, meaning it is the primary muscle causing the movement. In contrast, when extending the leg at the knee, such as when kicking, the quadriceps femoris acts as the antagonist to the biceps femoris, opposing its action. Thus, the biceps femoris and quadriceps femoris dynamically oppose each other during different movements of the knee.
When discussing cholesterol levels with a patient, which of the following is desirable?High cholesterol, low HDLHigh LDL, low cholesterolHigh cholesterol, high LDLHigh HDL, low LDLHigh HDL, High LDL
Answer:
Low LDL and High HDL
Explanation:
HDL refers to high-density lipoproteins and are considered as good cholesterol. HDL serves to channelize the cholesterol from body tissues and blood to the liver. The liver cells then eliminate the cholesterol. In this way, HDL serves to reduce the blood cholesterol level and should be present in a higher amount in the body.
On the other hand, LDL is low-density lipoproteins which carry the cholesterol from the liver to the body cells. Since LDL increases the cholesterol in body cells, it is considered as bad cholesterol and should be present in the lower level in the body.
Desirable cholesterol levels involve having high HDL (good cholesterol) and low LDL (bad cholesterol). High-density lipoproteins (HDL) help remove other types of cholesterol from the bloodstream, while low-density lipoproteins (LDL) promote cholesterol buildup and blockage in the arteries.
Explanation:When discussing cholesterol levels, the most desirable scenario is to have High HDL, Low LDL. HDL, or high-density lipoproteins, often referred to as 'good cholesterol', helps remove other forms of cholesterol from your bloodstream, thus reducing the risk of heart disease. LDL, or low-density lipoproteins, often called 'bad cholesterol', is the main source of cholesterol buildup and blockage in the arteries. Therefore, a high level of HDL and a low level of LDL is considered beneficial for your health.
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Helper T (TH) cells recognize antigens when they are bound to a(n)
A. hapten.
B. immunoglobulin.
C. natural killer cell.
D. major histocompatibility complex (MHC) protein.
Answer:
d
Explanation:
Helper T cell and inflammatory T cell TCRs recognise epitopes displayed by MHC class II molecules on the surface of antigen-presenting immune cells, including: macrophages that engulf foreign particles such as bacteria; dendritic cells that present antigen to T cells; and B cells that produce antibodies.
Final answer:
Helper T (TH) cells recognize antigens when bound to a major histocompatibility complex (MHC) protein. T cell receptors (TCRs) on T cells bind to the foreign protein fragments presented on MHC proteins by antigen-presenting cells (APCs).
Explanation:
Helper T (TH) cells recognize antigens when bound to a major histocompatibility complex (MHC) protein. T cells have antigen receptors on their surface called T cell receptors (TCRs), which bind to the foreign protein fragments (peptides) presented on MHC proteins by antigen-presenting cells (APCs) such as macrophages or dendritic cells. The TCRs recognize and bind simultaneously to the foreign protein fragment and the MHC protein on the APC surface.
Proteins are transported via axoplasmic transport at slow rates (0.5 to 2 mm per day) and fast rates (200 to 400 mm per day). The difference in transport rate directly results from:
a. the difference in the time spent per day in transport by kinesin on microtubules.
b. the site where the protein is synthesized
c. the substrate molecule used by the motor protein
d. the motor protein used to transport the proteins
Answer:
Option (a).
Explanation:
Protein is one of the most important biomolecules and a basic building block of the body. Axoplasmic transport of protein includes the transportation of protein to and from the neuron.
Axoplasmic transport of protein shows the difference in transportation rate because different proteins spent different time on microtubules during transport by the kinesin molecule.
Thus, the correct answer is option (a).
What is the difference between an endocrine and an exocrine gland?
Answer:
The difference between an Endocrine and an Exocrine Gland is that Exocrine Gland are those glands that pour their product of secretion to the outside of the body ( have secretion channels) and Endocrine Glands are those that pour their product of secretion (hormones) into the bloodstream ( have no secretion channels).
Explanation:
The glands are structures that can be constituted by one or several cells, and that are formed from epithelial tissue. Their function is to secrete various substances, such as hormones, and they are classified as endocrine and exocrine, according to the place where they discharge their secretions.
The Endocrine Glands are very vascular structures, that is, irrigated by a large network of blood capillaries, thin and porous walls. These glands produce hormones that are poured directly into the bloodstream and transported by the blood vessels to the target tissues, where they come to perform their function. According to the chemical nature of the hormones produced by the endocrine glands, the organelles of the cells that constitute them can reach different degrees of development. For example the pancreas secretes insulin, which allows the body to regulate blood sugar levels.
The Exocrine Glands secrete substances through ducts directed to the surface of the body or to the interior of some organs. For example, exocrine glands are mucus-producing goblet cells, present in mucosal epithelia such as the lining of the intestine, and the sweat, sebaceous, and mammary glands. Tears are also produced by exocrine glands.
Describe the pain associated with leukemia and explain the reason for it.
Answer:
Bone pain is associated with leukemia because large number of cancer cells are present in the bone marrow.
Explanation:
Leukemia may be defined as the cancer of blood cells. This cancer generally starts in the bone marrow and leads to uncontrolled division of the cell.
An individual suffering from leukemia may experience bone or joint pain. Bone pain is more common in lymphoblastic leukemia. The bone pain is mainly caused by the uncontrolled growth of cancer cell in the bone marrow.
1. A couple of mice with brown fur and black eyes had litter with the following distribution of traits: 9 with brown fur and black eyes, 3 with brown fur and red eyes, 3 with grey fur and black eyes, and one with grey fur and red eyes. Propose an explanation.
Answer:
The genotype of the couple of mice is heterozygous.
Explanation:
First, we going to classify each trait as dominant or recessive allele:
Brown fur: It’s a dominant allele because 12 of 16 mice have brown fur, therefore 75% of the litter have this trait.
Black eyes: It’s a dominant allele because 12 of 16 mice have black eyes, therefore 75% of the litter have this attribute.
Grey fur: It’s a recessive allele because only 4 of 16 mice have this trait, so 25% of the litter have grey fur.
Red eyes: It’s a recessive allele because 4 of 16 mice have red eyes, so 25% of the litter show this trait.
Second, we going to name each phenotype with a letter and use a capital letter for dominant allele or a small letter for recessive allele.
For the color of the fur, let’s use letter “F”:
F: Brown fur
f: Grey fur
For the color of the eyes, let’s use letter “E”:
E: Black eyes
e: Red eyes
The genotype of each phenotype is conformed by two letters that indicates, the recessive allele is showed in the phenotype only when both letters in the genotype are small letter.
For example, for fur, there are three combinations:
FF: Brown fur (two dominant alleles)
Ff: Brown fur (A dominant allele and a recessive allele)
ff: Grey fur (Two recessive alleles)
For eyes, there are also three combinations:
EE: Black eyes (two dominant alleles) (
Ee: Black eyes (A dominant allele and a recessive allele)
ee: Red eyes (Two recessive alleles)
When both allele of the genotype are dominant or recessive, it is heterozygous, if there are a dominant allele and a recessive one, it is a homozygous.
Since there are 7 mice that show recessive phenotype, that means the genotype of the couple of mice are heterozygous. Although, both mice show a dominant phenotype, the genotype have a dominant allele and a recessive allele.
The genotype for the couple of mice is:
FfEe x FfEe
So, when we apply the Mendel's third law, we got the results showed in the chart.
Groups of organisms with low biotic potential, such as gray whales, that produce at most one offspring every other year ________. A) are r-selected B) are K-selected C) are not subject to density-dependent limiting factors D) show the initial stages of the extinction process E) have escaped from the processes of natural selection and adaptation
Answer:
B) K - selected species
Explanation:
Usually, large in size individuals such as whales, hipopothamus, horses and bears are K-selected species. They have a low biotic potential which means, they produce small amount of individuals in the reproduction and possess relatively stable populations.
On the ther hand, species such as fleas, rats, and rabbits (between others) are rated r-selected species, which means they have a high biotic potential; have a large amount of individuals per birth.
Final answer:
Gray whales, which have low biotic potential and typically produce one offspring every other year, are categorized as K-selected species because they live long, mature late, and provide substantial parental care to their offspring. The correct answer is B) are K-selected.
Explanation:
The question tackles the reproductive strategies of different species, specifically focusing on the biotic potential and reproductive rates of grey whales. Organisms that have low biotic potential and produce few offspring at greater intervals, such as grey whales, are generally considered K-selected species. K-selected species, like grey whales and elephants, live long, mature late, and provide substantial parental care to their fewer offspring.
On the other hand, r-selected species are characterized by early maturation, short lifespans, and the production of many offspring with little to no parental care.
Therefore, the answer to the student's question is that groups of organisms with low biotic potential, such as gray whales, that produce at most one offspring every other year are B) K-selected.
Which neural term is a synonym for action potential?
Answer: We can express some synyms for action potential, such as, AP (action potential), nerve impulse, and conduction signal.
Explanation:
Nerve cells transmit information to each other to the others through electrical impulses called action potentials (PA), making the communication of neurons similar to a network of electronic circuits. Generally, action potentials are dependent on the activation of sodium channels (Na +), which open in response to variations in membrane potential and are therefore characterized as voltage-dependent.
The correct option is Option D (Nerve Impulse). An action potential, synonymous with a nerve impulse, is a brief electrical charge that travels along a neuron’s membrane. This process involves a rapid change in the membrane’s electrical potential. Depolarization is a key phase in action potential generation.
An action potential, also known as a nerve impulse, is a brief electrical charge that travels along the membrane of a neuron. This process involves a momentary change in the electrical potential of the neuron's membrane. During action potential generation, the cell membrane potential changes quickly from negative to positive due to the flow of sodium ions into the cell and potassium ions out of the cell, which is termed depolarization.The full question is available online. The question is :
Which neural term is a synonym for action potential?
a) Axoplasm
b) Axolemma
c) Synaptic knob
d) Nerve impulse
A second nerve impulse cannot be generated until ________. A. the Na ions have been pumped back into the cell B. the membrane potential has been reestablished C. proteins have been resynthesized D. all sodium gates are closed
Answer:
(B). the membrane potential has been reestablished
Explanation:
Nerve impulse can be defined as a signal that transmits along the nerve fibers. The neurons are said to be in resting phase when there is no nerve impulse.
When a stimulus is applied to resting membrane, sodium ions freely pass inside the cell and membrane is now said to be in depolarized phase. Due to this, a difference in electrical potential is generated across the membrane, known as nerve impulse or action potential.
When the action potential is over (after transmitting the nerve impulse through neuron) the cell membrane potential returns back by repolarizing the membrane.
Once the membrane potential is completely returned to its resting potential (when membrane potential is reestablished), the neurons become ready for second or next nerve stimulus.
Thus, the correct answer is option (B).
A second nerve impulse cannot be generated until the membrane potential has been re-established. Therefore option B is correct.
After a nerve impulse, the membrane potential of a neuron undergoes changes due to the movement of ions across the cell membrane.
During an action potential, the membrane depolarizes as sodium ions (Na+) rush into the cell, followed by repolarization as potassium ions (K+) move out of the cell.
Following the repolarization phase, the cell membrane needs to be restored to its resting state in order for another nerve impulse to be generated.
This process is called reestablishing the membrane potential. It involves the following steps: Sodium-Potassium Pump, Ion Channels, and Resting Membrane Potential.
Once the membrane potential is re-established, the neuron is ready to generate another action potential and transmit a new nerve impulse.
This process ensures that nerve impulses are transmitted in a coordinated and regulated manner.
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4) Select the two characteristics below that describe RNA.
it is double-stranded
the sugar is called ribose
is only found in the cell's nucleus
its nitrogenous bases are A, G, T, and C
is translated in the cytoplasm
Answer:
Option (2) and (5).
Explanation:
RNA is present as a genetic material in some viruses only. RNA is a single stranded molecule that can be found in the nucleus as well as cytoplasm. The nitrogenous bases present in RNA are adenine, uracil, guanine and cytosine.
RNA contains ribose sugar in its structure. The translation of RNA occur in the cytoplasm by the process known as translation.
Thus, the correct answer is option (2) and (5).
Which of the following statements is FALSE? Individuals produced by asexual reproduction are clones of the parent. Mitosis is the basis of asexual reproduction in many eukaryotes. Mitosis occurs in somatic cells whereas meiosis occurs in germ cells. Individuals produced by asexual reproduction are haploid because fertilization does not occur to restore the diploid chromosome number. None of the answer options is false
Answer:
Individuals produced by asexual reproduction are haploid because fertilization does not occur to restore the diploid chromosome number.
Explanation:
In humans, somatic cells are diploid cells, containing two sets of chromosomes (2n). These cells can be found in the skin, blood and muscle cells. The number of chromosomes (n) differs in different organisms, and in humans, the complete set (2n) comprises 46 chromosomes.
Haploid cells are found in gametes or germ cells, and contain only one set of chromosomes (n). An example of haploid cells is the cells found in sperm and eggs.
With this, we can conclude that the individuals produced by asexual reproduction are not haploid because fertilization occurs to restore the number of diploid chromosomes.
The false statement is that individuals produced by asexual reproduction are haploid due to the absence of fertilization; in reality, they are clones of the parent and maintain the same ploidy level, typically diploid, through mitosis.
Explanation:The statement that is FALSE among the options provided is: Individuals produced by asexual reproduction are haploid because fertilization does not occur to restore the diploid chromosome number. This is incorrect because individuals produced by asexual reproduction are actually clones of the parent and are typically diploid if the parent is diploid. This mode of reproduction does not involve the reduction of chromosome number that occurs during meiosis. Instead, it involves mitosis, a process where a eukaryotic cell divides to produce two genetically identical daughter cells, each with the same number of chromosomes as the parent cell.
In asexual reproduction, a single parent passes a complete copy of its genetic information to its offspring, thereby producing clones. This is different from sexual reproduction, where meiosis reduces the chromosome number by half to produce haploid gametes, and fertilization restores the diploid number when two gametes from different parents fuse.
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Match the following bacterial cell components to their major functions:
A. motility
B. determine cell shape; support and protect plasma membrane.
C. conjugation (exchange of plasmid DNA between cells)
D. cell attachment
E. protein synthesis
F. genetic material (DNA) storage
selectABCDEF 1. cell wall
selectABCDEF 2. nucleoid
selectABCDEF 3. ribosomes
selectABCDEF 4. fimbriae
selectABCDEF 5. pilus
selectABCDEF 6. flagella
Answer:
The correct options are cell wall- B, nucleoid- F, ribosome- E, fimbriae- D, pilus- C and flagella- A.
Explanation:
1. Bacterial cell wall- is an outer layer which is made of peptidoglycan or murein which provides structural support to the bacteria present outside the plasma membrane.
2. Nucleoid- an irregularly shaped region without nuclear membrane which contains the genophore or genetic material of bacteria.
3. Ribosome- are the organelle which is involved in the process of translation that is the synthesis of protein.
4. Fimbriae- thin and short appendage of the cell which helps in the attachment of the cell thus also called "attachment pilus".
5. Pilus- hairlike appendages which are involved in the horizontal transfer of genes through conjugation so also known as "conjugation pilus".
6. Flagella- hair-like appendage made up of microtubules which helps in locomotion of organisms.
Thus, the selected option is the correct answer.
Which of the following is not a difference between the autonomic nervous system and the somatic nervous system?
a.The number and types of neurotransmitters.
b.The presence of ganglia.
c.The number of motor neurons.
d.The involvement of the spinal cord.
Answer: It is the involvement of the spinal cord.
Explanation: Whether message via the nerve impulse is voluntary(somatic nervous system) or involuntary (autonomous nervous system) it has to pass through the spinal cord to the brain. Basic function of the spinal cord is to receive sensory information from body parts to the brain and from the brain to the body.
The difference between the autonomic and somatic nervous systems that is not valid is d) 'The involvement of the spinal cord', as both systems involve the spinal cord.
The question pertains to the differences between the autonomic nervous system and the somatic nervous system. Among the options provided, the one that is not a difference between the two systems is 'd. The involvement of the spinal cord'. This is because both the autonomic and somatic nervous systems involve the spinal cord as part of their pathways. Specifically, the somatic nervous system consists of a single motor neuron path that extends from the central nervous system to skeletal muscles and releases acetylcholine. In contrast, the autonomic nervous system, which includes the sympathetic and parasympathetic divisions, consists of a two-neuron pathway from the CNS to peripheral ganglia and then to the target organs, such as smooth muscles, cardiac muscles, or glands. The primary neurotransmitter for the parasympathetic system is acetylcholine, while in the sympathetic system, the postganglionic neurons release norepinephrine.
The gland in the chest where lymphocytes develop
Answer:
Thymus gland
Explanation:
The thymus gland in the chest is where lymphocytes develop.
It was found that a reversible inhibitor and a substrate bind an enzyme, but at different sites. The inhibitor was quite potent at reducing enzyme activity, but an analysis indicated it could not actually bind the enzyme unless the substrate was bound first. These results led to what conclusion?
Answer:
Uncompetitive inhibitor
Explanation:
There are two types of inhibitors: reversible (can detach enzyme) and irreversible (can’t detach enzyme).
Exist three types of reversible inhibitors: competitive inhibitors( inhibitor binds free enzyme, usually has the same shape as the substrate, and substrate cant binds enzyme), non-competitive inhibitors ( inhibitors bind the enzyme at a different site of substrate and change the enzyme conformation ) and uncompetitive inhibitor ( inhibitors bind the complex enzyme-substrate).
In this case, is an uncompetitive inhibitor, because we know that inhibitor is reversible, and the substrate must be bind with the enzyme so the uncompetitive inhibitor bind to the complex and stop the enzymatic activity. If the enzyme and the substrate are not together, the inhbitor can´t bind the enzyme.
The described scenario suggests that this is a case of allosteric inhibition, where the inhibitor binds at a different location from the active site and induces a conformational change in the enzyme that reduces its affinity for the substrate, thereby reducing enzyme activity.
Explanation:The scenario described fits the profile of an allosteric inhibition. An allosteric inhibitor is one that binds to an enzyme at a location other than the active site (hence, a different site from where the substrate binds). This inhibitor alters the enzyme's conformation (or shape), reducing the enzyme's affinity for its substrate, thus making the enzyme less efficient at binding with the substrate. In this case, the inhibitor doesn't bind unless the substrate is already bound, which strengthens the conclusion that this is allosteric inhibition.
With allosteric inhibition, the inhibitor doesn't compete for the active site (as in competitive inhibition) but instead changes the enzyme's structure, specifically the active sites on the enzyme's subunits, resulting in reduced efficiency in substrate binding. This is why despite binding at a different site, the inhibitor effectively reduces the enzyme's activity.
Moreover, it should be kept in mind that allosteric inhibition isn't the only way allosteric regulation can happen; there are also allosteric activators. While inhibitors decrease the enzyme's affinity for its substrate, activators increase it.
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Dynamothermal (regional) metamorphism occurs when ________. a. the upper surface of a body of rock develops a thick soil profile b. a pluton causes metamorphism in a small surrounding region c. regression of the sea leads to erosion of sedimentary cover on a body of rock d. rock becomes deeply buried during continental collision and mountain building
Answer:
d. rock becomes deeply buried during continental collision and mountain building
Explanation:
Dynamothermal (regional) metamorphism occurs when rock becomes deeply buried during continental collision and mountain building.
Dynamothermal (regional) metamorphism occurs when rock becomes deeply buried during continental collision and mountain building.
What is mountain building?Orogeny is just the way of mountain building, and it can be studied as a geological structural event, a topographical event, as well as a chronological event because it affects specific rock and crustal locations, causes recognizable structural features and occurs over a specific period of time.
What is collision?A collision should be any process by which two or perhaps more bodies quickly impose forces on one another.
Therefore, dynamothermal (regional) metamorphism occurs when rock becomes deeply buried during continental collision and mountain building.
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In genetic engineering, the structures called “sticky ends” result from what process? the results of mRNA after post-transcriptional modification the results of DNA following the work of helicase the changes produced by an inversion mutation the uneven cutting by most restriction enzymes
Answer:
Option). the uneven cutting by most restriction enzymes
Explanation:
Sticky ends can be defined as over-hanged DNA fragments of unequal length, having a terminal portion with unpaired nucleotides. These fragments are formed by a staggered cut on DNA molecules wit the help of restriction endonuclease enzymes.
These ends have complementary nucleotide bases that allow complementary base pairing between bases, and thus, known as sticky ends.
Thus, the correct answer is 'last option.'