Answer:
- Delivery of the sperm to the female gametophyte
- Protection of the male gametophyte
Explanation:
The pollen grain is a microspore present in angiosperms and gymnosperms, it contains the male gametophyte.
The pollen tube present in pollen grains and the way they are transported (by wind) allows these plants to require no water for reproduction.
In addition, the pollen grain has two very resistant walls (internal and external), composed mainly of cellulose, ensuring protection to the male gametophyte until it meets the female gamete.
Which of the following occurs in situations where more than one hormone produces the same effects at the target cell and their combined effects are amplified?
A. synergismB. antagonismC. summationD. permissiveness
Answer:
The correct answer will be option-A.
Explanation:
Hormones act on the target cells of the body in two ways: antagonism and synergism.
The synergism is the condition when two or more hormones act on the same target cells to produce more strong and amplifies results than they achieve individually. The most common example of synergism in the body is the effect of the follicle-stimulating hormones (FSH) and testosterone on sperm production.
Thus, option-A is the correct answer.
QUESTION 20
The strength of a base that only partly ionizes in solution would be described as _____.
A)dilute
B)concentrated
C)weak
D)strong
A base that partly ionizes in a solution is described as a weak base (option C), distinct from a strong base that ionizes almost completely.
The strength of a base that only partly ionizes in solution would be described as weak (option C). This is because a weak base is one that does not completely dissociate into its ions in solution. The key distinction between a weak base and a strong base is the degree of ionization. A strong base dissociates almost completely when dissolved in water, while a weak base only does so partially. Whether a solution is dilute or concentrated refers to the amount of solute in the solvent, and not the intrinsic strength of the acid or base.
After the drought of 1977, researchers on the island of Daphne Major hypothesized that medium ground finches that had large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. If this hypothesis is correct, what would you expect to observe if a population of these medium ground finches colonizes a nearby island where T. cistoides is the most abundant food for the next 1000 years?
Answer:
If a population of medium ground finches with large, deep beaks colonizes a nearby island where Tribulus cistoides is the most abundant food for the next 1000 years, it is expected that this finches population will dominate de island, displacing the smaller beaked birds.
Explanation:
Since large seeds will be available for the next 1000 years as the most abundant food, only birds with large beaks will be able to eat them. Smaller beaked birds won´t be able to feed on them, and eventually, they will starve because they won´t have any food. In this way, the finch population will rapidly change on the new island in favor of the medium ground finches with large, deep beaks.
Stellar evolution is the life cycle of a star. A cycle suggests that upon death of a star, another star is born. How is this possible? A.Stars never really die. B.The death is a black dwarf star. This type of death triggers the birth of a new star. C.The death is a red giant. This type of death emits red energy that forms a new star. D.The death is a supernova. This type of death can produce nebular clouds and trigger the birth of a new star.
Answer:
star never really die
Explanation:
Because stars dont die
Answer:
Option- B
The death is a black dwarf star. This type of death triggers the birth of a new star.Stars are comprised of a number of mixture of gases as we know that due to the losses that happens inside the celestial objects the energy inside which they posses runs out of stock or it decrease and it then form the red dwarf which is the magnanimous form of mixture of gases. On further contraction of this mass which is really due to the extensive amount of gravity been placed inside them, there is a formation of nebula or we can say more different celestial entity.And at the end if the star is not big enough or too large as compared to our sun, then it would turn into a black dwarf, or in other cases if the star which forms the nebula is too large then it will be then transformed into a black hole depending upon the size of the star.
please help me 40 points!!! im being timed and i only have 15 minutes!!!
The picture is a major macromolecule.
What best describes the function of this macromolecule?
A
It is broken down to provide usable chemical energy.
B
It stores and transmits genetic information.
C
It transports oxygen in the blood.
D
It helps plants retain water.
Answer:
B
Explanation:
This macromolecule is DNA. Its stored genetic information in form of genes that translate to functional or structural proteins that make up an organism. The DNA double helix is unzipped by helicases enzymes into single strands. RNA polymerase transcribes the single strands into mRNA. The mRNA is then translated into proteins by ribosomes. This is called the central dogma (DNA RNA Proteins).
During cell division, the DNA is replicated into two copies and each copy goes to each of the two daughter cells preserving, more or less, the same genetic code to the new cells.
Leaching, the recovery of copper from the drainage water of mines, as a method of the extraction of minerals, it was well established as early as the eighteenth century, but until about 25 years ago miners did not realize that bacteria take an active part in the process.a) as a method of the extraction of minerals, it was well establishedb) as a method of the extraction of minerals well establishedc) was a well-established method of mineral extractiond) was a well-established method of extracting mineral that wase) had been a method of mineral extraction, well established
"The correct option is c. was a well-established method of mineral extraction.
The sentence provided in the question is complex and requires a choice that fits grammatically and contextually. The sentence is discussing the historical context of leaching as a method for extracting copper, emphasizing that while the method was known, the role of bacteria was not understood until approximately 25 years ago from the time of writing. Let's evaluate the options: a) as a method of the extraction of minerals, it was well established - This option creates a non-restrictive clause with the commas, which is not incorrect, but it is somewhat awkward and less precise than the best answer. b) as a method of the extraction of minerals well established - This option is grammatically incorrect because it lacks a verb to connect ""as a method"" with ""well established."" c) was a well-established method of mineral extraction - This option is grammatically correct and clearly conveys that leaching was a recognized method for extracting minerals in the past. It fits the context of the sentence by indicating that the method was established before the discovery of bacteria's role. d) was a well-established method of extracting mineral that was - This option is incorrect because it ends with ""that was,"" which is grammatically incomplete and does not make sense in the context of the sentence. e) had been a method of mineral extraction, well established - This option uses the past perfect tense ""had been,"" which is not necessary since the simple past tense ""was"" suffices to indicate that leaching was established before the discovery of bacteria's role. Additionally, the comma before ""well established"" is unnecessary and disrupts the flow of the sentence. Therefore, option c is the most concise and grammatically correct choice that accurately reflects the intended meaning of the sentence."
Raven has just finished learning a list of nonsense words given to her by her psychology instructor as part of a class activity. She had 100 percent recall at the end of class. According to Ebbinghaus’s curve of forgetting, how quickly will Raven likely forget about 40 percent of the information she has just learned?
a. within the rst 20 minutes after leaving the classb. within the rst day after leaving the classc. nearly a week after the classd. nearly a month after the class
Answer:
Option (a).
Explanation:
Ebbinghaus Forgetting Curve may be defined as the curve that are used to determine the decreases ability of the brain to memorize the thing. This was first hypothesized by Ebbinghaus.
The ability of memorize the things will depend upon the individual and on the strength of the memory. As Raven was 100% recall the the end of class, she can forget the 40% memory by leaving at the rest 20 minutes after the class. The memory retain with her long that gas the high strength.
Thus, the correct answer is option (a).
Although he gave minilessons on using text factors, a teacher found that his students were still not internalizing and applying this information. Of the following, the best way to help students internalize the information would be for the teacher to:A) place the students in literature circlesB) demonstrate with a think-aloudC) require students to read nonfiction booksD) provide more time for sustained silent reading
Answer:
The correct answer is option B) "demonstrate with a think-aloud".
Explanation:
Think-aloud literally means to say one thoughts, expecting to other people would hear them. The strategy of describing the thoughts is very helpful for a teacher to achieve that his students internalize the information that is being given. If the teacher uses this approach, the student could see the teacher's perspective and would know what the teacher is thinking when he is using text factors. In consequence, the next time the student tries to use text factors she or he would know for certain what is the teacher approach.
3. What 20th century discovery has been instrumental to the field of genetic engineering by allowing researchers to cut and splice specific DNA fragments into microorganisms?
a) Small RNAs
b) Restriction enzymes
c) Ribozymes
d) The microbiome
Answer:
b) Restriction enzymes
Explanation:
Restriction enzymes are the endonucleases that recognize and cut the specific DNA sequence and breakdown the DNA into smaller fragments.
With the discovery of these enzymes, it became possible to cut the genome of microbes or any other organism at the specific site.
For example, the restriction sequence for the restriction enzyme EcoRI is 5' GAATTC 3' on one strand and it cuts between G and A of the sequence and between A and G on the complementary strand.
what is fetch, definition???
Answer:
achieve when sold
Explanation:
The mucosa of the appendix contains masses of lymphoid tissue (MALT) and therefore leukocytes capable of attacking bacteria are present in the appendix. During appendicitis, bacteria trapped in the lumen of the appendix are not effectively attacked because ______.
Answer: There is an inadequate blood supply to the appendix wall
Explanation: The appendix is a tube-shaped sac that's attached to the large intestine. It exists in humans and a small number of other mammals, including the koala and apes. In medical terms, it’s referred to as 'vermiform appendix' for its thin, worm-like shape.
According to researchers, the human digestive system is full of bacteria necessary to digest food. [1] When attack from diseases, sometimes these important kinds of bacteria are purged or killed off. In such situations, the appendix can act as a reserve for good bacteria. After the immune system beats off the disease, the bacteria emerge and re-colonize the gut.
During appendicitis, bacteria trapped in the lumen of the appendix are not effectively attacked because of the inadequate blood supply to the appendix wall. Therefore leukocytes are not able to migrate to the site of infection to attack the bacteria.
Bacteria trapped in the lumen of the appendix during appendicitis aren't effectively attacked because inflammation and swelling from the resulting inflammatory response create a physical obstacle that interferes with the immune response. This is despite the appendix housing the mucosa-associated lymphoid tissue (MALT), a critical component of the immune system that typically aids in fighting off bacteria.
Explanation:During appendicitis, bacteria trapped in the lumen of the appendix are not effectively attacked because the resultant inflammation and swelling can create a physical barrier that hinders the circulation of leukocytes and the conduction of the immune response. The mucosa-associated lymphoid tissue (MALT) in the appendix forms an integral part of the immune system, housing leukocytes that attack bacteria. Specialized endothelial cells, known as M (or microfold) cells in MALT, typically transport materials from the intestinal lumen to neighboring follicles to instigate immune responses against potential pathogens.
However, in the case of appendicitis, a blockage in the lumen can trigger these cells to incite an inflammatory response instead. That can lead to the appendix swelling, essentially creating a physical barrier that prevents leukocytes from effectively reaching and attacking the trapped bacteria.
Furthermore, this situation can be exacerbated by the presence of copious blood and lymphatic vessels in the lamina propria (the tissue layer beneath the MALT). When these vessels react to the inflammation by dilating and becoming permeable, tissue edema can ensue, further compromising the immune response.
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Put the following steps of Koch's postulates in order:
A. The suspected infectious agent must be isolated and grown outside the host.
B. The suspected infectious agent causes the disease when it is introduced to a healthy, experimental host.
C. The suspected infectious agent must be found in every case of the disease.
D. The suspected infectious agent must be found in the diseased experimental host.
Answer:
Koch's postulate correct order is - C, A, B, D.
Explanation:
Koch's postulates are given by Robert Koch a german bacteriologist and physician to form criteria to identify that if a particular is able to cause a disease or epidemic or not. It helped in bringing scientific clarity to this field.
The suspected infectious agent must be found in every case of the disease.
The suspected infectious agent must be isolated and grown outside the host.
The suspected infectious agent causes the disease when it is introduced to a healthy, experimental host.
The suspected infectious agent must be found in the diseased experimental host.
Thus, the correct order is - C, A, B, D.
Which of the following is true of the blood-brain barrier? a. The barrier is formed by cells that line the capillaries of the brain. b. The barrier is uniform, protecting all brain structures. c. The barrier functions to regulate the chemical composition of the extracellular fluid surrounding the brain cells. d. The barrier pumps glucose out of the brain into the bloodstream.
Answer:
The barrier functions to regulate the chemical composition of the extracellular fluid surrounding the brain cells.
Explanation:
Blood-brain barrier
It is a very selective semipermeable membrane , hence allow some specific substance to pass via it . This barrier separates the extracellular fluid in the central nervous system and the circulating blood from the brain .
The barrier is composed of the endothelial cells .
Passive diffusion is shown in this system , and allows molecules like the water , glucose , amino acid to pass .
It regulates the chemical composition of the fluid of brain cell .
The blood-brain barrier, formed by cells lining the brain's capillaries, functions to regulate the chemical composition of the extracellular fluid surrounding brain cells, and isn't uniformly protecting all brain structures. Its primary role is not to pump glucose out of the brain into the bloodstream.
Explanation:The blood-brain barrier (BBB) is crucial to the health and function of the Central Nervous System (CNS), notably the brain and spinal cord. Rooted in its unique arrangement of blood vessels, the BBB holds strict control over what can move out of the circulatory system and into the CNS, shielding it from toxins or pathogens that may be present.The barrier is indeed formed by cells lining the capillaries of the brain, primarily endothelial cells form tight junctions, limiting the transfer of blood components to the brain. This excludes most microbes, hence there is no normal microbiota in the CNS. Furthermore, the blood-brain barrier also functions to regulate the chemical composition of the extracellular fluid enveloping the brain cells, not to pump glucose out from the brain into the bloodstream.
However, it's not accurate that the BBB is uniformly protecting all brain structures. Certain areas of the brain, like the choroid plexus and parts of the hypothalamus, have a more permeable barrier to allow specific molecules to pass through.
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Two species of clams inhabit the same marine habitat along the Atlantic coast. One releases gametes into the water in early spring, and the second species releases gametes into the water in late summer. Which type of reproductive barrier is at work between these species?
Answer:
Temporal Isolation
Explanation:
The mechanisms of reproductive isolation that work before zygote formation are categorized as pre-zygotic isolation mechanisms. One such mechanism is the temporal isolation.
Here, two diverging populations exhibit differences in the timing of reproduction so as to prevent the possible interbreeding between them.
In the given example, two species of clams present in the same habitat prevent interbreeding among themselves as they release their gametes at a different time of year. One species release gametes in water in early spring while the other does the same during late summer.
Since gametes are not released at the same time, they cannot fuse together and interbreeding is not possible between the given two species.
In a species of snail, dark-shelled individuals are better hidden from bird predators in the shady forest, while light-shelled individuals are better hidden in well-lit brushy edge areas. If there were no areas of intermediate brightness in this habitat,which type of selection would act on shell color in these snails?
Answer:
Disruptive Selection
Explanation:
Disruptive selection is the type of natural selection wherein two extreme phenotypes are favored due to their survival and reproductive success over the intermediate phenotype. It results in two peaks of distribution in the normal distribution curve.
In the given example, two extreme phenotypes with respect to the shell color of snails are favored in two different habitats. Dark shelled snails exhibit survival advantage in the shady forest while the light shelled snails are favored in well-lit habitats.
Since two extreme shell colors are favored over the intermediate-range by natural selection, it represents disruptive selection.
You do a gram stain of an unknown bacterium and the teacher guarantees you that is it a member of family Enterobacteriaceae. However, your cells come out purple. What other clue might indicate that you do have a member of that family of bacteria?
a. tiny cocci bacilli in chains
b. tiny bacilli
c. rod-shaped cells with endospores
d. curved rods.
Answer:
The correct answer is c. rod-shaped cells with endospores
Explanation:
Most members of family Enterobacteriaceae can appear pink after gram staining due to porous membrane like Zymophilus, Pectinatus etc. Most of them form endospores which is a very tough outer covering formed by cells to resist the adverse condition. Many members of these family resides in intestine of animals and helps in food digestion.
These bacteria comes under phylum Firmicutes and mostly are rod shaped(bacillus). So when most of cells comes out purple the rod shaped cells with endospores indicates that gram stain contains the member of family Enterobacteriaceae.
The correct option is b. tiny bacilli clue might indicate that you do have a member of that family of bacteria.
When performing a Gram stain, members of the family Enterobacteriaceae are typically Gram-negative bacteria, which means they should appear pink or red under the microscope after the staining process. However, if the cells come out purple, it suggests that they have retained the crystal violet dye, which is characteristic of Gram-positive bacteria. This could be due to improper staining technique or the presence of a Gram-variable organism.
Despite the unexpected Gram stain result, the teacher's guarantee that the bacterium is a member of the family Enterobacteriaceae can be supported by other characteristics:
a. Tiny cocci bacilli in chains: This description does not match the typical morphology of Enterobacteriaceae, which are usually rod-shaped.
b. Tiny bacilli: This option is consistent with the typical morphology of Enterobacteriaceae, which are small rod-shaped bacteria.
c. Rod-shaped cells with endospores: While some rod-shaped bacteria form endospores, members of the family Enterobacteriaceae do not typically produce endospores.
d. Curved rods: This morphology is more characteristic of other bacterial families, such as the Vibrionaceae family, not Enterobacteriaceae.
Therefore, the presence of tiny bacilli (option b) would be a clue indicating that the bacterium is indeed a member of the family Enterobacteriaceae, despite the Gram stain result. It is important to consider other morphological and biochemical characteristics when identifying bacteria, especially when there is a discrepancy in staining results.
Ideally, the nasal septum will devide the nasal cavity equally, but it is common for this partition to be slightly off center. A deviated septum, however, is a condition in which the nasal septum is shifted significantly away from the midline. Explain how this abnormality may cause difficulty in breathing.
Answer:
A deviated septum occurs when bone and the cartilage that divides the nose septum become off-center which results in two unequal nasal septum. This makes one nasal chamber smaller and another larger.
This abnormality causes difficulty in breathing because of the congestion and blockage of the smaller nasal cavity. Due to this congestion airflow in the lungs is hindered which results in lack of oxygen and difficulty in breathing.
Apart from difficulty in breathing it can leads to nose bleeding, loud snoring during sleep, facial pain, headache, and in respiratory infections breathing become more difficult.
A deviated septum can develop due to some trauma or during surgery but some people are born with this abnormality.
The nasal septum is a structure that separates the nasal cavity into two halves. A deviated septum, a condition where the nasal septum deviates significantly from the midline, can cause difficulty in breathing by impeding normal airflow, particularly during exertion.
Explanation:The nasal septum is a flat, midline structure that separates the nasal cavity into two halves. It is formed by the perpendicular plate of the ethmoid bone, vomer bone, and septal cartilage. The septum contributes to the moistening and warming of air as it enters the nose, due to the surfaces of the conchae and the nasal mucosa.
When the nasal septum is significantly deviated from the midline in a condition known as a deviated septum, it can impede normal airflow, resulting in difficulty breathing. This happens because the deviation can block one side of the nose, reducing airflow and making it more difficult for air to pass freely through the nasal passages. This is especially noticeable during exertion when a higher volume of air is required.
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As Rick was filling out the loan application, he couldn't remember his previous address even though he had lived there for five years. Rick's memory of his current address was interfering with his memory of his old address, which is an example of:
Answer:
Retro Active Interference
Explanation:
This confusion of Rick's memory for his address for the previous one is attributed to Retro active interference.
The phenomena where recently learned memory of a person meddles with and blocks the review of previously learned data or memory is referred to as Retro active Interference.
This happens when the underlying demonstration of reviewing explicit data meddles with the recovery of the first data.
Small channels that form across the plasma membranes of adjacent cells
Answer:
Gap junctions
Explanation:
They allow adjacent cells to communicate. These channels form a close connection between cytoplasm because small molecules such as ions are able to pass through from cell to cell. Examples of cells with gap junctions are cells in heart muscle tissues. Gap junctions are found in animal cells and are akin to plasmodesmata in plant.
Which part of the compound light microscope is used to change magnification? Please provide an explanation along with your answer.
A.) Part A
B.) Part C
C.) Part E
D.) Part F
Answer:
Part C
because rotating the 3 knobs will increase magnification for more or less visibility depending on what you want to see relating to the size of the microscopic or eye-visible image.
The part of compound light microscope that is used to change magnification is Part C. That is option B.
A compound light microscope is an instrument that is used to magnify an image thereby separating it into minute details.
The light microscope has two sets of lenses:
The objective lens:The eye piece lens:The objective lens which is the part labelled C is used to change the magnification of the image of an object. This is done by selecting the desired magnification through the rotation of the nose piece.
Most light microscopes have two or three objective lenses attached to a rotating nose piece. These lenses usually are 5x, 10x, 40x, 100x. This means that a 10x lens magnifies the image of the object by 10 times.
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Pesticide use ________.
a) may be a necessary part of modern technological agriculture
b) can be eliminated by changing the season when crops are planted
c) will be eliminated as pests decrease as a consequence of years of pesticide use
d) poses no environmental threat in this country
e) will not be a problem as we learn to genetically modify predators
Answer: Option A.
Explanation:
Pesticide are defined as the substances which are used to control pests, and weeds in agricultural practices. Herbicide, insecticides, nematicide and fungicide are the examples of pesticides.
Now a days use of pesticide has become a necessary part of modern technological agriculture. Agricultural technology has evolved a lot from past and several benefits of pesticides are found that affect production and quality of crops. Other advantages of pesticides that makes its use necessary includes improve economic status of countries due to increases in yield using pesticide that reduces pests effect on yield; pesticides undergo photochemical transformation and produces metabolites which are non-toxic to human health and the environment; and Insecticides are used to control the insects which caused diseases like malaria.
Hence, the correct option is A.
Final answer:
Pesticide use a) may be a necessary part of modern technological agriculture.
Explanation:
The correct answer to the question about pesticide use is that it a) may be a necessary part of modern technological agriculture. Pesticides play a crucial role in controlling crop pests, which are mostly insects, and can significantly increase agricultural productivity when initially applied. However, over time, pesticides become less effective as pest populations evolve resistance. There's also the consideration of their impact on non-target species, including beneficial insects like honeybees, and environmental pollution affecting other ecosystems. Despite these concerns, the complexities of agriculture make the use of pesticides a continuing reality, although practices such as increasing landscape complexity to support natural pest enemies and reducing pesticide use can help mitigate some of the negative effects.
A truck carrying petroleum collided with a tree and has been leaking gas since the collision. Ecologists suggest the use of microorganisms to prevent soil pollution due to the leakage. Which method are the ecologists suggesting should be used?
Answer:
The method ecologists are suggesting is bio-remediation.
Explanation:
The treatment of contaminated or polluted areas such as any surface material, water or soil by using microorganisms is termed as bio-remediation. The microorganisms tend to degrade the pollutants. Also, the method of bio remediation is cheaper then any other alternative methods. Another subtle advantage of using the method of bio remediation over other methods is that the microorganisms can be genetically engineered to degrade certain type of pollutant.
Homeostasis is the maintenance of internal consistency. It’s a common principal in all living things and extends to pH. In a living system, what helps the organism maintain its pH homeostasis?
Answer:
Buffer systems
Explanation:
Living organisms maintain constant pH of both extracellular and intracellular fluids. The human body also maintains the pH of blood within the narrow range of 7.35 to 7.45. This is achieved with the help of buffer systems. Buffers are the chemicals that convert the strong acids or bases into their weak counterparts by removal or addition of protons.
For example, carbonic acid–bicarbonate buffer system of the human body wherein the bicarbonate ions serve as weak bases while the carbonic acid serves as a weak acid.
Under the conditions of higher H+ concentrations, the bicarbonate ion of the buffer system serves as a weak base and accepts the excess of the H+ to restore the normal range.
What refers to the role of a species in it's ecosystem and often relates to what it eats or what consumes it?
Answer:
ANSWER : NICHE
Explanation:
The particular role of a species or organism in its comprising ecosystem is termed as niche. Niche refers to every way that a specie interacts with its environment included both the biotic components as well as the abiotic components. Niche describes how well an organism is adapted for a particular environment. It tells us how well a species is for competing for food and other resources in that environment and how it is better for that environment.
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Cells store energy when:
A.) Ions are released into the bloodstream.
B.) They break down sucrose to glucose and fructose.
C.) A third phosphate group is bonded to an ADP molecule
D.) The third phosphate group breaks off from an ATP molecule.
Answer:C
Explanation:
Cell energy is stored when a phosphate group attaches to an ADP molecule.
How do cells store and release energy?• Adenosine triphosphate (ATP), also known as a cell's “energy currency, " is an essential molecule for a living cell.
• When a cell requires energy to perform any function, ATP splits off a phosphate from itself, resulting in the formation of adenosine diphosphate (ADP) and a phosphate. The energy released during the process of splitting ATP molecules is utilized to perform any cellular function.
• Similarly, when a cell has extra energy, it attaches a phosphate back to the ADP molecule. The process of the energy cycle can be shown as: ADP + P ⇔ ATP
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Algae in the genus Caulerpa typically grow to a length of over half a meter and have structures similar to stems, leaves, and roots. Reproduction occurs when adults produce sperm and eggs that fuse to form offspring. Each adult Caulerpa consists of just a single cell, however. Evaluate the following sentence and determine whether it is true or false. Explain your answer."Caulerpa must be a prokaryotic organism because one individual is made up of a single cell."
Answer:
Being an unicellular organisms has no relationship with being prokaryotic. The main prokaryotic feature is having the DNA free in the cytoplasm, or not surrounded by a membrane. Also most of the the time (but not always) gametes are produced by meiosis which is a type of cell division that is exclusive of eukaryotes.
Vitamins C and E are antioxidants that protect against attack by oxidants. The antioxidant vitamin needs to snuggle up to the polyunsaturated fatty acid. Predict which antioxidant vitamin will be better at doing this.
Answer:
Vitamin E
Explanation:
Vitamin E is a fat-soluble nutrient present in many foods. In the body, it acts as an antioxidant, by helping to protect cells against damage caused by free radicals. Vitamin E will have greater antioxidant power than Vitamin C, since it is fat soluble, which will allow it to be combined with fatty acids more easily.
Vitamin E is better at snuggling up to polyunsaturated fatty acids compared to Vitamin C.
Explanation:Both Vitamin C and Vitamin E are antioxidants that protect against attack by oxidants. However, in terms of snuggling up to polyunsaturated fatty acids, Vitamin E is better at doing this.
Free radicals react with lipoproteins and unsaturated fatty acids in cell membranes, removing an electron from those molecules and generating a new free radical. Antioxidants react with free radicals to stop these chain reactions. Vitamin E forms a more stable molecule or a less reactive free radical and thus prevents the oxidative degradation of lipids.
In contrast, Vitamin C primarily works in the aqueous (water) phase of cells and is not as effective in directly interacting with unsaturated fatty acids.
A geologist discovers that the number of fossils of a single species decreases significantly in higher rock layers compared to deeper rock layers. Which conclusion can best be drawn from this evidence?
Answer:
The species became less abundant
Explanation:
If the species decreases it doesn't necessarily means it has become extinct.
Answer:
This means that the number of individuals of this species has decreased over time.
Explanation:
When a rock is formed in one place, it goes through a process called weathering, which causes this rock to create layers over time. The deeper the layer, the older it is, on the other hand, the more superficial layers are younger. This is very important when cinetistas want to know how the population of a given species has increased or decreased over the years.
This occurs by visualizing the amount of fossils in each layer of the rock. If scientists can see that the number of fossils of a single species decreases significantly in the higher rock layers compared to the deeper layers, they can conclude that the number of members of that species has decreased over time.
Investigators wish to purify an enzyme—a serine protease—using affinity chromatography. They attach to the matrix of an affinity column an antibody molecule that binds specifically to a short sequence of amino acids located in the enzyme’s active site. When they apply a mixture of proteins to the column, the protease adheres to the column and the other proteins pass through. To extract their purified enzyme from the column, the investigators add a large excess of the peptide that the antibody recognizes. What should they expect to occur after this treatment?
After adding an excess of the specific peptide to the column, investigators should expect the serine protease to be displaced from the antibody due to competitive binding, allowing them to collect the purified enzyme.
Explanation:Purification of Serine Protease Using Affinity Chromatography
When using affinity chromatography to purify an enzyme such as a serine protease, investigators can attach an antibody that specifically binds to a sequence of amino acids in the enzyme's active site to the column's matrix.
During the purification process, the enzyme adheres to the column while other proteins do not.
To elute the bound serine protease, investigators can add an excess of the specific peptide recognized by the antibody.
This competitive process should result in the displacement of the serine protease from the column, allowing its collection in a now purified form.
The logic behind this method is based on the principle of competitive binding, where the free peptide competes with the bound enzyme for the antibody attached to the column.
Because a large excess of the peptide is added, it outcompetes the enzyme's binding to the antibody, thus releasing the enzyme into the solution where it can be collected.
What heart problem would be experienced by an individual whose ECG is seen at C?
a. ECG tracings showing normal and various abnormal rhythms.
b. The atria are not pumping blood.
c. The ventricles are not reaching systole in every cardiac cycle.
d. The heart is not pumping any blood at all.
e. The heart would pump with too much pressure (hypertension).
Answer:
The ventricles are not reaching systole in every cardiac cycle.
Explanation: