An allergic response occurs on the first exposure to an allergen. True or false:
Answers
An allergic response typically occurs on the second or subsequent exposure to an allergen, not the first. Hence, the answer is False.
When a person is exposed to an allergen for the first time, their immune system does not immediately recognize it as harmful. The immune system takes time to recognize and remember the allergen so that subsequent exposures can trigger an allergic response.
During the first exposure, the immune system may encounter the allergen, but it does not produce a significant response. However, it starts to produce specific antibodies, known as immunoglobulin E (IgE), which are designed to recognize and bind to the allergen.
On subsequent exposures, the allergen binds to the IgE antibodies on specialized immune cells called mast cells and basophils. This triggers the release of chemical substances, such as histamine, which cause allergy symptoms like itching, sneezing, swelling, and difficulty breathing.
It's important to note that the severity and timing of allergic responses can vary among individuals. Some people may experience immediate allergic reactions upon subsequent exposure to an allergen, while others may develop delayed allergic reactions. Additionally, there are rare cases where individuals may experience an allergic reaction on the first exposure to an allergen, but this is not the typical response.
In summary, an allergic response usually occurs on the second or subsequent exposure to an allergen, not the first.
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Related Questions
in humans and other mammals, the outside of each lung is lined with
Answers
In humans and other mammals, the outside of each lung is lined with a thin layer of tissue called the pleura. The pleura has two layers: the visceral pleura, which covers the surface of the lungs, and the parietal pleura, which lines the inside of the chest cavity.
The pleura plays an important role in protecting the lungs and helping them expand and contract during breathing. The visceral pleura adheres to the surface of the lungs and moves with them as they expand and contract. The parietal pleura is attached to the chest wall, diaphragm, and other structures in the chest cavity, creating a sealed sac around each lung.
The space between the two layers of pleura is called the pleural cavity. This cavity is filled with a small amount of lubricating fluid that allows the two layers of pleura to slide smoothly over each other during breathing. The pleura also helps to prevent the lungs from collapsing and provides a barrier against infection and inflammation in the chest cavity.
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what is the result of excitation-contraction coupling? (i.e., what does it accomplish? how does it bring together (couple) excitation and contraction? )
Answers
The result of excitation-contraction coupling is the contraction of muscle fibers. Excitation-contraction coupling is the process by which an action potential (excitation) leads to the generation of force (contraction) in muscle cells.
Here's how excitation-contraction coupling works:
1. An action potential is generated in the muscle cell membrane, usually initiated by a motor neuron.
2. The action potential propagates along the muscle cell membrane and deep into the cell through specialized invaginations called T-tubules.
3. The action potential in the T-tubules causes voltage-gated calcium channels in the adjacent sarcoplasmic reticulum (SR) to open.
4. Calcium ions (Ca2+) are released from the SR into the cytoplasm of the muscle cell.
5. The increase in intracellular Ca2+ concentration triggers a series of events that ultimately lead to muscle contraction.
6. Calcium ions bind to a protein called troponin, which is part of the thin filaments within the muscle cell.
7. The binding of calcium to troponin causes a conformational change in another protein called tropomyosin, which uncovers the active sites on the actin filament.
8. Once the active sites are exposed, myosin heads from the thick filaments bind to the actin, forming cross-bridges.
9. ATP is hydrolyzed, allowing the myosin heads to pull on the actin, resulting in muscle contraction.
10. The cycle of myosin binding, pulling, and detachment continues as long as calcium and ATP are available.
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You are given a compound that has a melting point of 560 c. you dissolve some of the compound in water and measure the ph of the resulting solution to be 11. you are told that the compound is either kcl, ca (oh)2, c6h12o6, or h2so4. which of these compounds were you given? explain.
Answers
When given a compound with a melting point of 560 C and its resulting solution's pH to be 11, the compound given is Ca(OH)2.
The solution is basic because Ca(OH)2 is a strong base, and its pH is relatively high. In addition, the compound has a melting point of 560 C, which is high and indicates that it is ionic; of the four compounds given, only Ca(OH)2 is ionic, and the rest are molecular compounds.
Ca(OH)2, commonly known as hydrated lime, slaked lime, or calcium hydroxide, is an inorganic compound that is used in many applications. In its anhydrous form, Ca(OH)2 has a melting point of 580 C, which is very similar to the given melting point. When Ca(OH)2 is dissolved in water, it produces a strongly alkaline solution, as demonstrated by the given pH of 11. As a result, the answer is Ca(OH)2.
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The crime scene investigation team arrives at a car crash scene and finds that both the drivers are taken away in an ambulance and there are no eyewitnesses. The investigation team needs to determine how fast the cars were going. Which action should crime scene investigators take? OA. collect glass samples and perform an analysis OB. use UV lamps to get an imprint off the speedometers OC. use forensic lamps to identify body fluids at the scene collect tiny particles of metal that flew off of the vehicles O D.
Answers
OB. If they’re determining how fast they were going
Carbohydrates, fats, and proteins needed for the normal functioning of our cells are obtained from
A. oxygen
B. food
C. carbon dioxide
D. vitamins
Answers
b
Explanation:
bec because food are the only thing that can contain carbohydrate fat and protein for human being
the number of protons in one atom of an alement determines the atoms _________, and the number of protons plus neutrons determines the ______________, of an element.
Answers
The number of protons in one atom of an element determines the atoms atomic number , and the number of protons plus neutrons determines the mass number, of an element.
A chemical element is a species of atoms, including the pure material made entirely of that species, that have a specific number of protons in their nuclei.
The atomic number is determined by the number of protons, and the atomic mass is determined by the sum of protons and neutrons.
The atomic number of an atom refers to how many protons it has. This number is crucial since it is exclusive to the atoms of a certain element. Every element has a variable number of protons in its atoms, yet every element has the same number of protons in all of its atoms.
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Sewage discharge and fertilizer runoff is detrimental to coral growth because it increases the ________. water temperature that kills zooxanthellae water temperature that results in coral bleaching amount of toxic synthetic chemicals which stimulate excessive bacterial growth salinity of the water that results in coral bleaching amount of inorganic nutrients in the water that stimulates excessive algal growth
Answers
Answer:
The correct answer is - amount of inorganic nutrients in the water that stimulates excessive algal growth.
Explanation:
Fertilizers, sewage discharge and industrial runoff has various chemicls enrich with the inorganic compound and elements that causes eutrophication of the the water body.
Eutrophication causes increase in the number of phytoplanktons and algal growth that is stimulates by the amount of inorganic nutrients.
Thus, the correct answer is - amount of inorganic nutrients that leads to excess growth of algae.
(ii) Explain whether the nitrate ions are taken up by the root by diffusion, active transport or both
processes. Justify your answer.
Answers
Answer:
Only by active transport.
Explanation:
This is because diffussion is possible only with gases and the nitrate ions passes through nitrogen fixing bacterials known as azotobacta.
FILL THE BLANK. The bacterial infection that is referred to as _____ is characterized by vesicles or sacs that rupture and form a golden crust.
a. Lupus
b. Eczema
c. Filariasis
d. Impetigo
Answers
a highly contagious skin infection that causes red sores on the face.
Name the juice stored in the gall bladder
Answers
Answer: The juice stored in the gallbladder is called "Bile".
Explanation: :b
Which of the following is the technically correct way to refer to womans frontal genitalia? A. vagina. B. vulva. C. perineum. D. enchanted castle.
Answers
Answer:
The technically correct way to refer to a woman's is B. vulva. The term vagina specifically refers to the internal canal, while the vulva includes the external genitalia such as the , and vaginal opening. The perineum is the area of skin between the vulva and anus. The term "enchanted castle" is not a medically or scientifically recognized term for the female genitalia.
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Explanation:
How did these puppies end up with toenail thicknesses that are different from one another even though they have the same parents? how did the gene combinations result in the different traits?.
Answers
Reason may be that the parents have passed on two different genes which results in different thickness of the toenails.
Mendel stated that different gene combinations in the parents can result in definite ratios of dominant and recessive traits. for example if we cross two hybrid parents with each carrying one dominant and one recessive gene it will result in different combination of genes.
Genetic variations can also arise from a normal process in which genetic material is rearranged or recombine as a cell is getting ready to divide . Genetic variations are also responsible for altering the gene activity or protein function can introduce different traits in an organism.
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The scientific explanation for global warming is very dependent on the _______ atom. a. chlorine b. carbon c. oxygen d. hydrogen Please select the best answer from the choices provided A B C D
Answers
Answer:
B. carbon
Explanation:
edge 2020
The scientific explanation for global warming is very dependent on the carbon atom as the majority of emissions contain compounds of carbon.
What is an atom?An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.
The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.
Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.
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Please answer the question above
Answers
Answer:
Having large number of stomata in a plant will increase the percentage of transpiration which is the water loss.
The reaction of photosynthesis decreases, as water is one of the main source needed in plants to photosynthesize.
As a result of too much water loss, will leads the plant to death.
what is measurement
Answers
Measurement is defined as the act of measuring or the size of something. An example of measurement means the use of a ruler to determine the length of a piece of paper. An example of measurement is 15" by 25".
Answer:
This is the act of measuring something or the act of taking the length, weight or height of something,e.t.c.
Explanation:
What would you use to measure an amount of solid sodium chloride(NaCl) crystals to add to a 30 mL solution?
A. 10 ml graduated cylinder.
B. Scale that can weigh up to 250 lbs.
C. Triple Beam Balance that measures to the nearest 0.1 grams.
D. Spectrophotometer that measures between 100 and 900 nanometers.
Answers
Answer:
Option C, Triple Beam Balance that measures to the nearest 0.1 grams
Explanation:
A Triple Beam Balance can measure mass of substances very accurately
For this case, a measurement device is required which can measure the mass of small quantity of salt for dissolving in 30 ml of solution.
A graduated cylinder measure volume so this would not help. A Spectrophotometer measures the intensity of light so this would not help. A Scale that can weight up to 250 lbs would not work for this case as small weight is to be measured.
Option D would be correct
What particles bond together to
form molecules?
A. Atoms
B. Neutrons
C. Compounds
D. Protons
Answers
Answer:
Atoms
Explanation:
Answer:
A. Atoms
Explanation:
There is a common skeletal architecture inside the limbs of most tetrapods. What is the pattern of shared bones?.
Answers
The pattern of shared bones in all the tetrapods is "one bone, two bones, many and then digits".
The humerus in the arm and the femur in the leg are two bones that articulate with a series of tiny blobs that link with the fingers or toes. All limb architecture is based on this design. In this manner, all the tetrapods share a common skeletal architecture.
The four limbs of tetrapods serve as an illustration of homologous features. Mice, crocodiles, birds, bats, and bats all have four limbs. Bony fish and sharks don't. Tetrapods evolved four limbs, and their offspring have retained this trait. Having four limbs is therefore a homology.
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Can someone give me a description of a biologist at least 2 sentences
Answers
Answer:
A scientist specializing in the science of biology is a biologist. Biologists observe, explore, and ask questions about topics in fields such as health, technology, and the environment.
Explanation:
Thymine is to DNA as uracil is to
A. RNA
B. adenine
C. ATP
D. Protein
Answers
Answer:
A. RNA
Explanation:
DNA has the chemical base of thymine, while RNA does not.
Instead, RNA has the base of uracil, to replace thymine.
Since the analogy relates thymine to DNA, uracil must be related to RNA.
So, A is the correct answer.
Thymine is to DNA as Uracil is to RNA.
Persian cats often have certain diseases and disorders, especially of the eye and nose since their heads have an unusual shape. Persian cats were developed by artificial selection by humans.
Which of the following traits is deliberately selected for when breeding Persian cats?
A.
flat faces
B.
inherited diseases
C.
genetic diversity
D.
all of these
Answers
Answer:
the answer is A
Explanation:
It couldn't be D or C because you don't want to give your cat a diseases and so that means it couldn't be D which is all of the above.
Crop rotation is a method of soil conservation because _______. a. the land produces more than one type of crop b. it requires plowing and tilling that reduces soil compaction c. it does not use the same parcel of land in sequential seasons d. it avoids the depletion of soil nutrients please select the best answer from the choices provided a b c d.
Answers
Crop rotation prevents the depletion of soil nutrients, making it a form of soil conservation.
The correct option is D.
What is a conservation of soil?In order to sustain soil fertility and productivity, soil must be protected from erosion and other forms of deterioration. Water use and watershed management are typically included.
What is a crop rotation ?Crop rotation is the practice of planting different crops sequentially on the same plot of land to improve soil health, optimize nutrients in the soil, and combat pest and weed pressure. Because it prevents the depletion of soil nutrients, crop rotation is a technique for conserving soil.
A soil conservation is what?To preserve soil fertility and productivity, soil conservation entails preventing erosion and other forms of deterioration. Management of watersheds and water consumption are typically included.
The importance of crop rotation:Crop rotation aids in preserving the soil's structure and nutritional content as well as preventing the establishment of soilborne pests in the garden. When one crop is sown in the same location every year.
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which statement about the hershey-chase experiment is false?
Answers
The Hershey-Chase experiment is known as one of the most famous experiments in molecular biology. It was conducted in 1952 by Alfred Hershey and Martha Chase and confirmed that DNA is the genetic material of viruses.
Let's take a look at some of the statements about the Hershey-Chase experiment and determine which one is false:The Hershey-Chase experiment involved labeling the bacteriophage DNA and protein with radioactive isotopes. This statement is true. The Hershey-Chase experiment involved infecting the bacteria with labeled viruses. This statement is also true.
The Hershey-Chase experiment demonstrated that DNA is the genetic material of viruses. This statement is true as well. The Hershey-Chase experiment demonstrated that proteins are the genetic material of viruses. This statement is false. The Hershey-Chase experiment proved that DNA is the genetic material of viruses.
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A student read that liquid extracted from an Aloe vera plant promotes the healing of burned tissue. She decided to investigate the effect of different concentrations of Aloe vera extract on the regeneration (regrowth of lost or damaged tissue) rate in planaria. Planaria are small flatworms known for their ability to regenerate.
The student used a sterile scalpel to cut each of 30 planaria in half. This gave her 10 heads and 10 tails for each of three experimental groups. The planaria were kept in separate Petri dishes in the same amount of water and at the same temperature. Group 1 received 0% Aloe vera extract, Group 2 received a 20% concentration of the extract, and Group 3 received a 40% concentration. On days 7, 10, and 14, she recorded the amount of tissue regeneration in all three groups. She observed that the group with 20% Aloe vera added regenerated more slowly than the group with 40% added.
A reasonable inference based on these results would be that
(1) Aloe vera affected the rate of cell division, resulting in an increased rate of regeneration
(2) the control group, which received no Aloe vera, did not regenerate
(3) if she applied 30% Aloe vera to a group, it would regenerate tissue more rapidly than the 40% group (4) the application of Aloe vera to earthworms would have no effect on tissue regeneration
Answers
The experiment did not provide any evidence to support the idea that Aloe vera extract affects the rate of cell division. Additionally, since the control group was not described as having no regeneration, it is unlikely that the second inference is correct. It is also not possible to infer that a 30% concentration of Aloe vera extract would result in faster regeneration than a 40% concentration based on the results of the experiment. Finally, since the experiment was conducted on planaria, it is not appropriate to make any conclusions about the effect of Aloe vera extract on earthworms.
Give me brainliest answer, please.
which region of the brain is larger in humans and primates than in other vertebrates?
Answers
Which region of the brain is larger in humans and primates than in other vertebrates?
A. cerebellum
B. midbrain
C. spinal cord
D. cerebral cortex
D
Which of the following is NOT essential for protein synthesis? *
ribosomes
tRNA
mRNA
carbohydrates
Answers
Answer:
carbohydrates
Explanation:
What monthly compounding nominal interest rate is earned on an investment that doubles in 8 years? Select one: O a. 8.60% O b. 8.50% O c. 8.80% O d. 8.70% O e. 8.40%
Answers
The monthly compounding nominal interest rate earned on the investment that doubles in 8 years is 8.80%.
The correct option is C.
What will be the monthly compound nominal interest?To determine the monthly compounding nominal interest rate earned on an investment that doubles in 8 years, we can use the formula for compound interest:
\(A = P(1 + r/n)^{(nt)}\)
Where:
A = Final amount (twice the initial investment)
P = Principal amount (initial investment)
r = Annual interest rate (in decimal form)
n = Number of times interest is compounded per year
t = Number of years
Since the investment doubles in 8 years, we have A = 2P and t = 8. Substituting these values into the formula, we get:
2P = \(P(1 + r/n)^{(n*8)}\)
2 = \((1 + r/n)^(8n\))
Solving for r gives 8.80%
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DNA is the genetic material that makes up living things, and folic acid plays an important role in the formation of DNA. Jon wants to study the effect of folic acid on DNA formation in microbes. Which statement accurately describe the variables in this study? A. The amount of folic acid and DNA synthesized are both dependent variables. B. The amount of folic acid and DNA synthesized are both independent variables. C. The amount of folic acid is the independent variable, and the DNA synthesized is the dependent variable. D. The amount of folic acid is the dependent variable, and the DNA synthesized is the independent variable. E. The amount of folic acid and DNA synthesized are neither dependent nor independent variables.
Answers
Answer:
The correct answer is - C. The amount of folic acid is the independent variable, and the DNA synthesized is the dependent variable.
Explanation:
DNA is the genetic material of most of the living organisms. In this question, Joe wants to study to see the effect of folic acid on the synthesis of the DNA. Folic acid ae the essential nutrients or vitamin for the synthesis of nitrogen bases of the DNA that are purines and pyrimidines. A dependent variable and an independent variable are two important part of any experiment.
A dependent variable is a variable being tested and measured. In the experiment Jon is conducting, the amount of DNA becomes a dependent variable that is being tested and measured in the presence of folic acid. And folic acid is the independent variable tested to check the formation of DNA in bacteria.
Thus, the correct answer is - C. The amount of folic acid is the independent variable, and the DNA synthesized is the dependent variable.
Answer:
The amount of folic acid is the independent variable, and the DNA synthesized is the dependent variable.
Explanation:
Edmentum
Which microfossils are useful for paleotemperature determination
using the oxygen isotope ratios of their shells?
Answers
The microfossils that are useful for paleotemperature determination using the oxygen isotope ratios of their shells are foraminifera.
Foraminifera are tiny marine animals that have been living for millions of years. Their shells are made up of calcium carbonate and are well-preserved in sediments. The shells of these microorganisms are widely used in paleoceanography to determine past climatic conditions. Paleoceanography is the study of the history of the oceans in the geological past using sediments and fossils. It helps us to understand how the oceans and climate have changed over time.
Paleotemperature is the measure of the temperature that existed in past geological ages. The temperature is determined by various means, including studying the growth rings of trees, ice cores, and microfossils, and others. Microfossils are microscopic fossils that are found in rocks and sediments that help in reconstructing past environmental and climatic conditions.
Oxygen isotope ratio is the measure of the relative abundance of oxygen isotopes 18O and 16O in a sample. The ratio of the two isotopes changes as a result of temperature changes. The ratio is used to reconstruct past temperature changes.
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why is glucose important to all life on Earth
Answers
Answer:
Glucose is arguably the most important monosaccharide because it is used in respiration to provide energy for cells.
Explanation:
The energy stored in the bonds of glucose molecule is converted by a series of reactions into energy that is usable by cells.