I believe it to be B!
Answer:
Decline Overshoot
Explanation:
Odyseyware
The table below shows the number of chromosome pairs for various
organisms
Organism
Number of
Chromosome Pairs
Hare
24
Hyena
20
Kangaroo
6
Meerkat
36
)
Which organism can produce the highest number of genetically different
gametes?
Answer:
The correct answer will be option- Meerkat with 36 chromosome pairs
Explanation:
Genetic diversity in organisms takes place by the process recombination which takes place during cell division through meiosis.
The process of meiosis takes place during the gamete formation in organisms. During prophase I of meiosis, the exchange of DNA between sister chromatids takes place mediated by the formation of the synapse between chromosomes.
If the number of chromosomes in an organism will be high then there will be more probability of the genetic recombination process in those organisms.
So the organism with a high number of chromosome pairs can have the maximum chances of genetic recombination and genetic diversity. Thus, the selected option is the correct answer.
A scientist discovers a new microscopic structure and hypothesizes that it is a living organism. Which of the following characteristics would support the contention that this "organism" may be alive?
a. It contains DNA.
b. It consists of a single cell.
c. It maintains a constant interval environment.
d. All of the above.
Answer:
The correct answer will be option-D.
Explanation:
Biologists have identified eight characteristic feature of a living organism which distinguishes the living organism from non-living organism.
The features are that organisms should contain: cells, heredity material, metabolism, reproduction, sensitivity, homeostasis, growth and development.
In the given question, when the scientist hypothesized that structure is living organism then it should show all the options provided as all of these features are shared by the living organism.
Thus, option-D is the correct answer.
All of the following are properties of membranes EXCEPT:
a. supramolecular assemblies.
b. define boundaries of cellular components.
c. spontaneous assemblies resulting from hydrophobic interactions.
d. identical protein and lipid composition in the major organelles.
e. none, all are true.
Answer:
D
Explanation:
What happens during RNA splicing? RNA polymerase adds nucleotides to an mRNA strand. Enzymes cut introns out of an mRNA strand. A cap and tail are added to an mRNA strand. Transfer RNA is removed from an mRNA strand.
Answer:
It makes the RNA strand shorter
Explanation:
It is to make the process easier and quicker
Answer:
B (Enzymes cut introns out of an mRNA strand)
Explanation:
When an RNA transcript is first made in an eukaryotic cell, it is considered a pre-mRNA. Eukaryotes undergo processing of the pre-mRNA strand immediately after transcription. The genes of an eukaryote are split up into parts that are expressed as RNA products and parts that are not. The parts that contains the actual coding regions and are expressed are called EXONS while the parts removed from in between the exons and referred to as "junk sequences" are called INTRONS.
Introns and exons alternate with each other along the length of the gene. Introns are usually considered the non-coding regions because they don't seem to code for any protein, hence they are removed before the mRNA product is finally ready for translation. This post- transcriptional process is called RNA SPLICING. RNA SPLICING can be likened to the process of removing the chaff (introns) from the wheat (exons). It is the removal of introns and joining of exons in eukaryotic mRNA.
Splicing is carried out by SPLICEOSOMES ( a protein and RNA complex), which removes introns from the genes in mRNA. They locate the ends of the INTRONS, cut them away from the EXONS, and join the ends of adjacent exons together. Once the entire gene is devoid of introns, the process of RNA splicing is complete.
It is worthy to note that, not only do the introns not carry information to build a protein, they actually have to be removed in order for the mRNA to encode a protein with the right sequence. If the spliceosome fails to remove an intron, an mRNA with extra "junk" in it will be made, and a wrong protein will get produced during translation.
Which of the following clues would tell you if a cell is prokaryotic or eukaryotic?a. whether or not the cell carries out cellular metabolismb. whether or not the cell contains DNAc. the presence or absence of ribosomesd. whether or not the cell is partitioned by internal membranese. the presence or absence of a rigid cell wall
Answer:
d. whether or not the cell is partitioned by internal membranes.
Explanation:
The prokaryotic cells are those which do not have a defined or definite nucleus because the nucleus is not bounded by the nuclear membrane. This type of nucleus is called nucleon. The prokaryotic cell also does not have membrane-bound cell organelles. Thus, the prokaryotic cell is not partitioned by internal membranes.
Whereas, a eukaryotic cell has a well-defined or definite nucleus and membrane-bound organelles such as mitochondria, chloroplasts, Golgi apparatus, endoplasmic reticulum. Thus, the eukaryotic cell is partitioned by internal membranes.
A chemical imbalance in the body can cause the heart to stop pumping blood, which in turn will cause other tissues and organs to cease functioning. This observation supports the view that
Answer:
all levels of organisation within an organism are interdependent
Explanation:
An organism has different levels of organization within itself that, the levels are s follows: cell ----> tissues----> organs----> organ systems and there are further different organ systems present within an organism.Even though the organisms have a different level of organization, still there is an interdependence amongst these levels and all these different levels have to coordinate and work together so that the body can function normally. Therefore, a chemical imbalance in the body which may occur due to the nervous/endocrine system can cause the heart to stop pumping blood which is, in turn, a part of the cardiovascular system and this may further affect other tissues and organs and these may stop functioning. Thus this clearly shows how different levels coordinate and work to carry on norma functioning of the body.___________ is/are a type of neurotransmitter with similar properties to morphine.
Answer:
Endorphin is a type of neurotransmitter with similar properties to morphine.
Explanation:
Endorphins are a large group of peptide hormones in humans and other animals. Endorphins are produced by the pituitary gland and nervous system. They are helping to reduce pain, they are releasing in responding to pain and stress, They are also releasing in other activities such as eating, exercise etc.
Other benefits of endorphins includes:
Reducing the weight.
Reducing stress and anxiety.
Helping in deal with pain during childbirth.
Reducing the symptoms of depression.
The strongest muscle contractions are normally achieved by ________.
a) increasing the stimulation up to the maximal stimulus
b) increasing stimulus above the threshold
c) increasing stimulus above the treppe stimulus
d) recruiting small and medium muscle fibers
Answer:
a) increasing the stimulation up to the maximal stimulus
Explanation:
The strength of a muscle contraction is determined by:
Level of motor unit recruitment: the size and number of motor neurons being stimulated in a particular muscle. Muscle cross-sectional area: The greater the cross-sectional area of the muscle, the more muscle fibres that can be activated simultaneously. Muscle stretch: A muscle fibre can shorten to about 50 % to 60 % of its length, but it will be less efficient if it is already short.That’s why many athletes use a brief dynamic stretch sequence as a warm-up prior to their strength work.Number 1 is the only necessary factor for your answer.
The strongest muscle contractions are achieved by a) increasing the stimulation up to the maximal stimulus, which activates all available muscle fibres that can participate in the contraction.
Explanation:The strongest muscle contractions are normally achieved by a) increasing the stimulation up to the maximal stimulus. This is referred to as maximal tetanic stimulation. When a muscle fibre is exposed to a rapid series of stimuli, it reaches a point where it is fully contracted, and additional stimuli do not increase contraction strength.
This indicates that all the available muscle fibres that can participate in the contraction have been recruited. In other words, additional stimuli do not cause an increase in contraction force because all the muscle fibres are already engaged. This state of maximal contraction of a muscle fibre is referred to as a maximal stimulus.
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how do organisms carry out chemical activity of life?
A. through homeostasis
B. through asexual reproduction
C. by increasing metabolism
Answer:
I believe c
Explanation:
Which of the following is NOT an example of an epigenetic phenomenon provided by Dr. Carey on evidence that genetic identity does not lead to identical phenotypes in organisms?
a) kittens turn into cats
b) Maggots turn into flies
c) Some reptiles' genders are determined by the temperature of their nests
d) Humans have 200 different types of cells that develop from 1 DNA code
In humans, every cell in the body contains the same DNA code, which consists of the entire set of genetic instructions. The answer is d) Humans have 200 different types of cells that develop from 1 DNA code.
During development, cells undergo a process called epigenetic regulation, which involves modifications that control gene expression without altering the DNA sequence itself. Epigenetic modifications include chemical modifications to DNA, such as methylation, as well as modifications to histone proteins that package DNA.
Dr. Carey provided evidence that genetic identity does not lead to identical phenotypes in organisms through various examples of epigenetic phenomena. However, the fact that humans have 200 different types of cells that develop from 1 DNA code is not an example of an epigenetic phenomenon. It is a result of cellular differentiation and specialization during development, where different cells express different genes and perform specific functions, but it does not involve epigenetic modifications.
Therefore, the answer is d) Humans have 200 different types of cells that develop from 1 DNA code.
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On a NASA mission that was looking for life on Mars, soil samples were taken and measured for the breakdown of nutrients and the production of carbon dioxide gas. Which characteristic of life would this test measure?
What process is shown in the diagram below?
Answer:
my answer is the use of restriction enzymes.
Answer:
Use of restriction enzymes.
Explanation:
Restriction enzymes are also known as molecule scissors in the recombinant DNA technology. Two main types of restriction endonuclease are exonuclease and endonuclease.
The main function of the endonucleases is to cut the DNA fragments at the specific site. In the diagram, the restriction enzymes function has been shown. The restriction site of the enzyme has been specified and depicted in the picture.
Thus, the correct answer is option (C).
Close examination of an organ reveals a lining of multiple layers of cells. The layers are avascular and regenerate well. One surface of the cells is open to the internal cavity of the organ and protection and absorption are its functions. This tissue is probably:
Answer:
Epithelial Tissue
Explanation:
The epithelial tissue can be classified according to the amount of layers, such as simple epithelium (formed by a single cell layer) or stratified epithelium (formed by more than one cell layer).
In addition, this tissue is avascular, in other words, it has no proper blood supply. Its nutrient transport usually occurs by diffusion through connective tissue.
The epithelium layers are able to regenerate quickly and easily when destroyed. Being a coating tissue, its cells have high healing power.
The epithelial tissue has two opposite sides, the outside of the epithelium(cavity), is known as the apical surface, and the inside is called the basal surface (this surface receives nutrients from the connective tissue by diffusion).
Cells on both surfaces are tightly connected, providing protection to the underlying connective tissue.
Finally, epithelial tissue also participates in the process of absorption of substances through the intestinal epithelium.
Individuals in a large insect population display wide variation in the shape of their nectar-gathering mouthparts. A new food source, with flowers of different shapes, replaces the previous one, and insects with shorter, thicker mouthparts are much more efficient at gathering nectar from the new type of flower. Over multiple generations, what will likely happen to the variation of mouth parts within the population of insects?
Answer:
Variation of mouth parts will decrease
Explanation:
It is given that the insect population has wide variation in shape of nectar gathering mouth parts. Without any disturbance this variation would continue to exist and would be passed on to subsequent generations.
Now the flower shape has changed which leads to efficient collection of nectar by shorter, thicker mouth parts. Insects with such mouth parts would be more competent than others and hence would thrive in population. They will pass on these traits to the next generations too and ultimately shorter, thicker mouth parts would be preferred over other types of mouth parts which will reduce the variation in population. However the variation would not completely cease to exist.
Differences in female and male reproductive biology have led to different mating strategies for men and women. This is an example of what developmental perspective?
Answer: Evolutionary
Explanation:
Evolution of the male and female reproductive organs is necessary for the advancement of mating strategies that range from simple to complex living beings. This is a kind of adaptation those which have phenotypic characteristics favourable to attract the mates will reproduce the offspring. These traits will be passed on to the progeny and evolution of the species will take place.
What type of tissue has cells that are tightly packed
Answer:
The answer would be the epithelial tissue.
Explanation:
Epithelial tissue. The cells in epithelial tissue are tightly packed together with very little intercellular matrix. Because the tissues form coverings and linings, the cells have one free surface that is not in contact with other cells.
which of the following is true about the results of dr. harris experiment?
A. the results of the experiment may reinforce or weaken either hypothesis.
B. the results of the experiment must support and reinforce dr harris hypothesis
C. the results of the experiment must and reinforce the opposing hypothesis
Answer:
B
Explanation:
In an isotonic contraction, the muscle ________. A. rapidly resynthesizes creatine phosphate and ATP B. does not change in length but increases tension C. never converts pyruvate to lactate D. changes in length and moves the "load"
Answer:
Option D " changes in length and moves the "load"
Explanation:
What means ' isotonic contraction' ?
⇒ Isotonic contractions maintain constant tension in the muscle as the muscle changes length.
This means that option B "does not change in length but increases tension" doesn't apply. (This is isometric)
Option A says : " Rapidly resynthesizes creatine phosphate and ATP
Creatine phosphate breakdown is the most rapid method available to resynthesize ATP. The next fastest is glycolysis followed by aerobic metabolism in the tricarboxylic acid cycle (Krebs' cycle).
Option C says " never converts pyruvate to lactate".
Pyruvate is converted to lactate in anaerobic conditions, by the enzyme Lactate dehydrogenase. If pyruvate never gets converted to lactate it means this enzyme is missing.
Option D says :"Changes in length and moves the load. This is the definition of an isotonic contraction. So option D is correct !
An isotonic contraction is when the muscle changes in length to move a load, maintaining constant tension, which is different from isometric contractions where muscle length remains unchanged.
Explanation:In an isotonic contraction, the muscle changes in length and moves the "load". Unlike isometric contractions where muscle length does not change, isotonic contractions involve a change in muscle length while maintaining constant tension throughout the contraction. There are two types of isotonic contractions: concentric, where the muscle shortens, and eccentric, where the muscle lengthens. During a concentric isotonic contraction, for example, the biceps brachii muscle contracts to lift a weight, shortening as it does so and decreasing the angle of the elbow joint. Conversely, during an eccentric contraction, the muscle lengthens while lowering a weight in a controlled manner, and the angle of the elbow joint increases.
In an isotonic contraction, the muscle changes in length and moves the 'load'. This means that the muscle contracts and shortens, causing movement.
For the statements below indicate whether it is a hypothesis, theory, natural law or if it is not a scientific statement at all. Provide an explanation for your reasoning.
Statement 1: By increasing the amount of sun exposure the growth of a tomato plant will increase.
Statement 2: Energy cannot be created or destroyed
Statement 3: When newly industrialized parts of Britain became polluted in the nineteenth century, smoke killed lichens growing on trees and blackened their bark. Pale colored moths which had been well camouflaged before when they rested on tree trunks became very conspicuous and were easily found and eaten by birds. Rare dark moths, which had been conspicuous before, were now well camouflaged in the black background. Birds switched from eating mainly dark moths to pale moths. Over time, the most common moth color changed from pale to dark. Natural selection had caused a change in the British moth population.
Answer:
Statement 1: hypothesis
Statement 2: natural law
Statement 3: theory
Explanation:
1) An hypothesis is a proposed explanation for a phenomenon. It provides a suggested outcome. It needs to be tested through experimentation.
The statement says that an increase in sun exposure, increases the tomato plant growth, which is a suggested outcome and it can be tested.
2) Energy cannot be created or destroyed, is the first law of thermodynamics.
A scientific law is the description of an observed phenomenon. Without an explanation of the causes behind it.
3) A scientific theory is the explanation of a given phenomenon, based on a large body of empirical data.
This why after the pale and dark moths example, it says: Natural Selection had caused a change in the British moth population.
It is a theory that explains the phenomenon quoted.
Sickle cell disease (SCD) is caused by a recessive version of the hemoglobin gene. In the US, SCD occurs in about 0.2% of the newborn babies. In some African countries, 4% of the newborn babies have sickle cell. Out of a random sample of 10,000 newborn babies in the US, how many would you expect to be homozygous for the normal, dominant hemoglobin genotype assuming Hardy Weinberg equilibrium?
Final answer:
In the US, where 0.2% of newborns are affected by sickle cell disease, the expected number of homozygous dominant individuals in a sample of 10,000 newborns is estimated to be approximately 9,126, based on the Hardy Weinberg equilibrium calculations.
Explanation:
Sickle cell disease (SCD) is an autosomal recessive genetic disorder characterized by the production of abnormal hemoglobin, named hemoglobin S, which leads to the sickling of red blood cells. This sickling can block blood flow and cause a range of health issues. In the United States, 0.2% of newborns are affected by SCD.
In a population in Hardy Weinberg equilibrium, we can use the Hardy Weinberg principle to calculate the frequency of homozygous dominant individuals. The frequency of the recessive allele 'q' can be determined by taking the square root of the disease prevalence, which is 0.002 in the US (since 0.2% = 0.002). Applying this, we get q = √0.002 ≈ 0.0447. The frequency of the dominant allele 'p' can be calculated as p = 1 - q which gives us p ≈ 1 - 0.0447 = 0.9553.
The frequency of homozygous dominant individuals is p². So, p² = (0.9553)² ≈ 0.9126. In a sample of 10,000 newborns, the number of individuals homozygous for the normal hemoglobin genotype would be expected to be 10,000 * 0.9126 ≈ 9126.
__________ is an enzyme that prevents telomeres from degrading by adding more repeating dna to the ends.
Answer:
Telomerase
Explanation:
Telomerase enzyme catalyze the reaction of maintaining the length of telomeres, preventing it from degradation or shortening by adding guanine rich sequences towards the end of DNA. Telomeres basic function is to maintain and protect our genetic information because every time DNA replicates a short piece of chromosome is lost.
What is the basic function of the outer ear?
a. to filter out high-intensity sound waves that can be harmful
b. to amplify low-intensity sounds to detectable levels
c. to protect the hair cells
d. to concentrate and funnel sound waves to the eardrum
e. to filter out low-intensity sound waves that can be harmful.
Answer: Option D.
Explanation:
Outer ear is the external part of ear called pinna with a helical shape.
Pinna helps in collecting sound waves and guide them to the eardrum.
The pinna helps in assisting the difference in pressure inside and outside the ear. Pinna function sin resisting the high pressure of sound waves inside the ear and makes the smoother sound to transmit which passes into the auditory canal.
Hence, the correct option is D.
The basic function of the outer ear is to concentrate and funnel sound waves to the eardrum.
Explanation:The basic function of the outer ear is to concentrate and funnel sound waves to the eardrum. It acts like a funnel, capturing and directing sound waves towards the ear canal and eardrum. This helps in collecting and transmitting sound efficiently. The shape of the outer ear helps in determining the direction of sound as well.
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A scientist wants to perform a test that will indicate whether a nucleic acid sample is composed of RNA or DNA. Testing for the presence of which of the following is most appropriate in this situation?A) phosphate
B) nitrogen
C) guanine
D) uracil
E) thymine
Final answer:
To determine if a nucleic acid sample is RNA or DNA, testing for the presence of uracil is most appropriate, as it only occurs in RNA, not DNA.
Explanation:
A scientist who wants to perform a test to determine whether a nucleic acid sample is composed of RNA or DNA should test for the presence of the nitrogenous base uracil. DNA contains the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T), while RNA contains adenine, cytosine, guanine, and uracil but not thymine. The presence of the uracil would indicate that the sample is RNA, and the absence would indicate that the sample is likely DNA. Similarly, if thymine is present, the nucleic acid is more likely to be the DNA as RNA does not contain thymine.
When soft-centered chocolates are made, the enzyme invertase is used to convert sucrose into glucose and fructose. This causes the chocolate centers to become softer and sweeter.
Identify the substrate, enzyme, and product in the above reaction.
An in advance thanks to anyone who replies! :D
The substrate in the reaction is sucrose, the enzyme used is invertase and the product formed is glucose.
What is a substrate?A substance on which certain enzymes acts and forms product is referred to as a substrate.
In the given situation, the sucrose is converted into product called glucose by the action of enzyme invertase.
Thus, the substrate in the reaction is sucrose, the enzyme used is invertase and the product formed is glucose.
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The answers are: a) The enzyme should not be heated above 45°C to avoid denaturation. b) Invertase accelerates the conversion of sucrose into glucose and fructose by decreasing the activation energy of the hydrolysis reaction. c) Increasing the substrate concentration can diminish the impact of inhibitors on the enzyme's activity.
Using Invertase in Soft-Centred Chocolates:
Invertase is an enzyme crucial in the production of soft-centred chocolates as it converts sucrose into the smaller molecules glucose and fructose. This conversion makes the centres softer and sweeter.
A) Temperature Sensitivity of Invertase:
Invertase must not be heated to temperatures above 45°C because enzymes are proteins that can denature at high temperatures. Denaturation causes the enzyme to lose its structure and, consequently, its functional activity, meaning it would no longer catalyze the conversion of sucrose to glucose and fructose efficiently.
B) Mechanism of Action
Invertase increases the rate of conversion of sucrose into glucose and fructose by lowering the activation energy of the hydrolysis reaction. This enzyme binds to the sucrose molecule at its active site, facilitating the breaking of the glycosidic bond between glucose and fructose more efficiently than would occur in the absence of the enzyme.
C) Effect of an Inhibitor
The effect of an inhibitor on invertase may be reduced by increasing the concentration of the substrate (sucrose) because there will be more substrate molecules available to bind to the enzyme’s active sites.
This reduces the chances of the inhibitor molecules binding to the enzyme instead of the substrate, thereby allowing the enzyme to continue catalyzing the reaction.
Complete Question: -
When soft-centred chocolates are made, the enzyme invertase is used to convert sucrose into the smaller molecules glucode and fructose. This causes the centres of the chocolates to become softer and sweeter.
a) state why the invertase must not be heated to temperatures above 45°.
b) state how invertase increases the rate of conversion of sucrose into glucose and fructose.
c) Explain why the effect of an inhibitor on an enzyme may be reduced by increasing the concentration of the substrate
Nucleic acids are important information storage molecules present in virtually every cell. Which processes is carried out by a cell when it accesses that information in the DNA of the genes?
Answer:
Transcription
Explanation:
The DNA is stored in the nucleus of the cell. The DNA has the sequence information of every gene. This means that depending on the DNA sequence, we are going to have a particular protein. The transcription is a process within the cell in which an enzyme called polymerase enters the nucleus and transcribes the DNA into another molecule, RNA. Let's say that this process makes another "copy" of the nucleic acid sequence, but now the RNA is able to get out of the nucleus carrying genetic information into the cytoplasm. In the cytoplasm, the RNA is translated into protein. During the translation, a ribosome "reads" the RNA and builds the protein depending on the nucleic acid sequence. To sum up, we can say that the transcription is the first process involved in accessing the information from the DNA.
When a cell accesses information in the DNA of genes, it carries out the processes of transcription and translation. These processes convert DNA information into an RNA formate that's used to construct proteins.
Explanation:The processes carried out by a cell when it accesses information in the DNA of the genes are transcription and translation.
In transcription, the information stored in the DNA is converted into RNA, specifically messenger RNA (mRNA). This process occurs in the nucleus of the cell. The mRNA then moves to the ribosome in the cell cytoplasm where translation takes place.
During translation, the mRNA sequence is used to build a protein, with each three-letter 'codon' of RNA setting the position of a particular amino acid in the protein. Hence, both these processes together aid in forming proteins, which perform many vital functions in the body.
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What is a biofilm? A layer of sugars that persist even after bacteria have been killed by antibiotics A group of bacteria that accumulate in layers and secrete an protective extracellular material Free-floating bacteria that move through the blood to other sites A bacterial cell that secretes an extensive network of fibers around its cell wall
Answer:
A group of bacteria that accumulate in layers and secrete an protective extracellular material.
Explanation:
The biofilm is a natural way how the bacteria get together to survive in an ecosystem or in another living thing. They build little by little this kind of building with different layers of bacteria that secrets a polymer, this protection polymer could be useful to protect the colony or to be attach to another cell or to a tissue. In medicine and in veterinarian studies is interesting because can be useful to create a film to protect some injuries.
Answer: A group of bacteria that accumulate in layers and secrete an protective extracellular material
Explanation:
Biofilm comprises any spectrum of microorganisms, including pathogens in which cells stick to each other and to a surface, so they become adherent cells. These cells become embedded within an extracellular matrix that is composed of extracellular polymeric substances (polysaccharides, lipids, proteins and DNA) which surrounds and protects cells. For this reason, bacterial biofilms cause chronic infections because they show increased tolerance to antibiotics.
After a period of rapid growth (log phase), bacterial growth rates will slow and enter the stationary phase. The number of viable cells no longer increases, but instead stays constant. In this activity you will indicate the statements that correctly describe what is happening during stationary phase. Reasons?
A. The number of cells that are dying is balanced by the number of new cells that are being formed.
B. Cells are not increasing in number because they have not yet adjusted to the nutrient availability in the new media.
C. Harmful waste products may be accumulating.
D. The cells are likely running out of nutrients.
Answer:
A. The number of cells that are dying is balanced by the number of new cells that are being formed.
C. Harmful waste products may be accumulating.
D. The cells are likely running out of nutrients.
Explanation:
During the stationary phase, the number of viable cells remains constant. This may be due to a balance between cell division and cell death wherein the total number of newly formed cells and the cells undergoing death are equal.
Nutrient limitation is one of the several factors that make the microbial cells to enter the stationary phase. Depletion of nutrients slows down the population growth.
Accumulation of toxic waste products as it occurs during the growth of anaerobic bacteria also adversely affects the population growth.
For example, the accumulation of lactic acid and other organic acids (by-products of anaerobic respiration) inhibits the growth of the population by making the medium acidic.
A student is provided with a pure culture and asked to make a three-phase streak plate. The student takes a sample of the culture and streaks the first sector of the plate. What is the next step?
Answer:
The following step is to sterilize the wire loop, turn the plate 90 degrees, collect some organisms from the first area and continue to streak on the second area. Repeat for the third area.
Explanation:
The goal of three-phase streak is to obtain isolated colonies in the plate. To do this, the culture is diluted by spreading it through the entire plate.
In the first phase, one third of the plate is used to streak the initial inoculum in a zig-zag motion. As the wire spreads, the densitiy of organisms diminishes and colonies start to be further apart. Doing this only one time, is usually not enough to obtain isolated or separated colonies. So two more phases are used.
Before the second phase, the wire is sterilized, and colonies are collected by passing through the first area two or three times, so the inoculum now is much smaller than at the beginning. The organisms are spread in the second third of the plate, also in a zig-zag motion.
The same process is repeated in the third phase, by filling the remaining area of the plate.
By doing this, it is very probable that the initial culture is diluted enough to obtain single, isolated colonies in the plate which can then be grown separately in order to identify them.
A person’s work, social, and family environments can have a strong influence on eating and activity behaviors. When these factors are positive, they can help a person maintain a healthy weight. However, too many negative influences can contribute to obesity. Which of the following are not examples of societal influences that can contribute to obesity?
Select all that apply
a. food commercials during a popular television show
b. an individual's self-esteem
c. a person adopting American habits after moving from a different country
d. a person's resting metabolic rate
e. reasonable cost and availability of a wide variety of television, movie, and computer gaming options
Answer:
The correct answers are options b and d.
Explanation:
Obesity refers to a complex ailment that comprises an excessive concentration of body fat. It refers to a medical condition, which enhances the threat of other diseases and health issues like diabetes, heart disease, a certain type of cancers, and high blood pressure.
There are many causes why some individuals exhibit difficulty in preventing obesity. Generally, obesity results from a combination of social, environmental and inherited factors, apart from this it also depends upon one's personal diet and exercise choices.
Some of the risk factors for the development of the condition are family inheritance and influences, an unhealthy diet, and inactivity.
Some of the societal influences that can contribute to the condition is getting influenced by the food commercials displayed in between the television shows, adoption of unhealthy habits, and easier accessibility of movie, television, and computer games that enhances the sedentary lifestyle of an individual.
However, of the mentioned options, the self-esteem of an individual, and the resting metabolic rate of the individual do not contribute to obesity. Thus, the mentioned options are not examples of societal elements contributing to obesity.
The opposable big toea) is present in nonhuman primates but not humans, because humans lost this feature. b) is only found in Old World primates. c) is present in all primates. d) is present in nonhuman primates but not humans, because primates evolved this feature.
Answer:
a) is present in honhuman primates but not humans, because humans lost this feature.
Explanation:
The opposable big toe is a trait that helps to primates to climb trees easily. Humans' ancestors started to walk in two legs, this created a needing for better stability, so a fixed toe became to evolve to allow our bipedal locomotion.
Therefore, options b and c are wrong. Option d is wrong too because it implies that the group "primates" is newer than "humans", and in fact, "humans" is part of the group "primates", so this is not the correct answer.
The opposable big toe is present in all primates, including humans. Its functionality has been crucial for evolution allowing efficient gripping in many tasks. Though less opposable in humans due to evolution favoring walking, it is not entirely lost.
Explanation:The opposable big toe is a characteristic found in all primates, including humans. The opposable toe has been crucial in primate evolution, allowing for efficient gripping and manipulation of objects, which has been instrumental in tasks such as foraging for food and navigating arboreal environments.
The toe of humans is not as opposable as those of non-human primates. As humans evolved to walk on two legs (bipedalism), the toe evolved to provide balance and propulsion during walking and running, reducing its opposability to an extent, but not losing it entirely.
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