Answer:
The selective agent according to the scenario of the experiment is the antibiotic streptomycin.
Explanation:
A selective agent is an environmental factor that has a dramatic impact on the mortality rate of any organism. In this scenario of the experiment, the antibiotic streptomycin is the selective agent because as described, after the incubation period of the two agar plates, the plate with antibiotic streptomycin only has a few colonies which proves that the antibiotic streptomycin since it had an impact on the mortality rate of the E. Coli bacteria.
Answer:
The agent chosen according to the experimental form is the antibiotic streptomycin.
10. How do photosynthesis and cellular respiration differ?
O a. Photosynthesis uses food and cellular respiration produces food
О
b. Photosynthesis gives off oxygen and cellular respiration uses oxygen
c. Photosynthesis uses oxygen and cellular respiration uses carbon dioxide
d. Photosynthesis breaks down carbohydrates and cellular respiration produces them
Answer:
B
Explanation:
Photosynthesis involves the use of energy from sunlight, water and carbon dioxide to produce glucose and oxygen. Cellular respiration uses glucose and oxygen to produce carbon dioxide and water.
1. The Devonian period is considered the Age of Fishes. Would you expect
to find a tetrapod (animal with four legs) fossil closer to the
Carboniferous period or the Silurian period? Why?
Answer:
You would find one closer to the Carboniferous period.
Explanation:
You would find them closer to there because all life started out in the ocean and it took several eras for the land creatures to develop legs and the first era to have them is the Permian era and towards the end of the Carboniferous period. While the Silurina era was much earlier then both and still heavily influenced by crustaceons and other such sea creatures.
Since the first tetrapods appeared at the end of the Devonian period, it is expected to find tetrapods fossils closer to the Carboniferous than to the Silurian period.
--------------------
The paleozoic era goes from 570 to 250 ma ago.
The era is composed of the following periods
CAMBRIC (570-490 ma)ORDOVICIC (490-443 ma)SILURIAN (440-400 ma)DEVONIAN (400-360 ma)CARBONIFEROUS (360-290 ma)PERMIC (290-250 ma)SILURIC (440-400 ma)
Gondwana was already formed. Laurasia was in its formation process
This is a recovery stage after the big massive Ordovician extinction.
Trilobites diversification and occurs bivalves' radiation.
The first gnathostomes appear.
First records of terrestrial vascular plants ⇒ small and with no supporting structures, inhabiting the water margins.
DEVONIAN (400-360 ma)
There are new adaptative strategies that separate even more the marine environment from the terrestrial one. Age of FishesDefinitive colonization and diversification of species in the terrestrial environment.During this period, among other events, emerged the lineage that would later originate tetrapods, by the end of the period. The first Ichthyostega emerges, which could be the ancestor of amphibians.Expansion and diversification of plantsFirsts terrestrial arthropods emerged. Coevolution with plants started. A big massive extinction occurred at the end of the period that severely affected the marine environment. Occurs a gradual replacement of terrestrial plants.
CARBONIFER (360-290 ma)
Begins Pangea formationThere is an ecological rechange in the ocean after the extinctionAmphibians emerge on the ground.The first reptiles appear as anapsids, synapsids, diapsids.Complete independence from water. There was a diversification of horsetails and tree ferns, pro-gymnosperms, and gymnosperms.Insects proliferation.
According to this information, by the end of Devonian period the firsts tetrapods appeared.
During the Carbonifeous period, after the devonian massive extinction amphibians and reptiles appeared.
These sequences indicate that tetrapod fossils are closer to the Carboniferous period than the Silurian period.
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What do all vertebrates and invertebrates have in common?
A) They are prokaryotic.
B)They are covered by an outer skeleton.
C)They are multicellular.
D)They are bilaterally symmetrical.
Answer:
C. They are multicellular.
Explanation:
Answer:
C. They are multicellular
Explanation:
Animal Cells
- All animals are eukaryotes
- All animals are multicellular
What are two ways bacteria and protists can be helpful to people?
all of the cell theory? (4 points)
Oa
Every living thing is composed of cells.
Ob
c
Cells come from pre-existing cells.
Cells are the basic unit and structure of all living things.
Od
Every cell has a nucleus that contains genetic material.
Indicate the type of testing each sentence describes. 1. Chromosomes from a sample of cells are stained and analyzed microscopically. Karyotyping 2. A DNA probe that hybridizes to a particular gene can be used to determine if a gene is present, absent or altered. (Click to select) 3. Antibodies are used to detect the presence or absence of a protein. (Click to select) 4. The enzymatic activity of a protein can be assayed in vitro. (Click to select)
Answer:
1. Karyotyping
2. In situ hybridization
3. Immunological (immunoblotting)
4. Biochemical (enzyme assay)
Explanation:
Karyotyping is the procedure in which pictures of the chromosomes are taken in order to identify and classify them according to their sizes, lengths, centromere positions, banding patterns, etc. In karyotiping, the chromosomes are stained to be clearly seen under a light microscope. In situ hybridization is a technique where complementary DNA oligonucleotides (either DNA or RNA) are used as probes to localize a specific segment of nucleic acid in a histologic section. Immunoblotting (western blotting) is a sensitive assay where antibodies are used to mark a protein, thereby enabling the identification of target proteins by exploiting the recognition specificity mechanism between antigens and antibodies. An enzyme assay is a technique used to measure the consumption rate of a given substrate or its production rate over time. Enzyme assays can be classified into four types: initial rate, transient kinetics, relaxation and progress curve assays.
Eukaryotic organisms can be single-celled or multicellular.
11. Which of the following is a function of a protein
Answer:
Produces vital body structures, providing energy, providing cell structure, maintaining fluid balance, act as buffers, contributes to immune function.
Explanation:
Functions of proteins include:
A. transport of materialsC. structure of your bodyD. enzymes to speed up chemical reactionsF. movement of musclesH. chemical hormonesI. recognition and communication between cellsOptions A, C, D, F, H and I are correct.
Proteins are macromolecules composed of amino acids and play essential roles in various biological processes. They have diverse functions in the body, contributing to its structure, metabolism, and overall functioning.
Proteins involved in transport facilitate the movement of substances across cell membranes or throughout the body, allowing for the uptake and distribution of nutrients, ions, and other molecules. Examples include transport proteins in the blood, such as hemoglobin that carries oxygen.
Proteins contribute to the structure of the body, providing support, strength, and flexibility to tissues and organs. They form the structural framework of cells, muscles, bones, and connective tissues.
Enzymes are proteins that act as catalysts, speeding up chemical reactions in the body by lowering the activation energy required. They play a crucial role in metabolic pathways and are involved in processes such as digestion, energy production, and DNA replication.
Proteins are integral to muscle contraction and movement. They are responsible for generating force and enabling movement of skeletal muscles.
Certain proteins function as chemical hormones, regulating physiological processes and signaling between cells and tissues. Examples include insulin, growth hormones, and thyroid hormones.
Proteins are involved in cell recognition and communication, facilitating interactions between cells and coordinating cellular activities. They play a role in immune responses, cell signaling, and cell adhesion.
However, genetic code, insulation, and providing a quick burst of energy are not primarily attributed to proteins. The genetic code is carried by DNA and RNA molecules, while insulation is primarily provided by adipose tissue. Quick bursts of energy are predominantly fueled by carbohydrates.
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The complete question is:
Which of the following are functions of proteins?
A. transport of materialsB. genetic codeC. structure of your bodyD. enzymes to speed up chemical reactionsE. provide insulationF. movement of musclesG. provide a quick burst of energyH. chemical hormonesI. recognition and communication between cellsWhy does surface tension occur?
What do comets and astroids have in common
Answer:
Asteroids and comets have a few things in common. They are both celestial bodies orbiting our Sun, and they both can have unusual orbits, sometimes straying close to Earth or the other planets. They are both “leftovers” — made from materials from the formation of our Solar System 4.5 billion years ago.
Explanation:
How are rhizomes involved in asexual reproduction of ferns?
Answer:
The sporophytes of ferns grow through the rhizome
Explanation:
The gametophyte are responsible for sexual reproduction in plants while the sporophytes are usually responsible for asexual reproduction in plants.
Sporophytes are found in the rhizomes of plants and they help in the asexual reproduction.
This is how rhizomes are involved in asexual reproduction of ferns
Which of the following blood vessels carries blood from the tissues back to the heart?a) arteriesb) arteriolesc) aortad) veinse) capillaries
Answer:
Veinules
Explanation:
Veinules are smaller veins blood vessels that carries deoxygenated or poorly oxygenated blood from the tissues back to the heart except pulmonary veins and umblical veins
After the blood move from the capillaries, it enter smallest veins called veinules and then continually flows into the larger veins till it get to the heart.
Which statement describes a scientific theory
Answer:
here
Explanation:
A scientific theory is an explanation of an aspect of the natural world that can be repeatedly tested and verified in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results. Where possible, theories are tested under controlled conditions in an experiment.
In order to prepare an optimal heat-fixed bacterial smear for staining, one must be aware of a couple of factors that may lead to poor results; briefly explain these. Why is it necessary to heat fix a smear for simple staining?
Answer:
The answer is below
Explanation:
Some of the factors that may lead to poor results in an optimal heat-fixed bacterial smear for staining are the following:
1. Thickness of the smear: In a situation whereby the smear is too thick, it would be impossible to perform adequate decolorization.
2. Quantity of Decolorizer: if the quantity of the decolorizer or reagent is concentrated, the quality of the stain will be affected
3. Age of the culture: Older cultures have multiple ruptured and dead cells, which result in staining Gram-negative.
4. Duration of Decolorization: Overheated smear during heat fixing, often leads to the rupture of cell walls.
The reason it is necessary to heat fix a smear for simple staining is that:
Heat fixing affects bacterial enzymes original state, which hinders their cell digestion parts, thereby leading to the breaking of the cell. The heat also improves the steadfastness of bacterial cells to the slide.
It is essential to heat and fix a smear for simple staining as it helps the bacteria to get attached with the slide. However, one must also be aware of the factors, which may lead to poor results.
What is heat fixation?It is a laboratory method used commonly in histology, cell biology, and pathology in which a slide with a specimen like bacteria is passed via the source of heat for many times.
It is an essential step in the procedure of staining as the heat fixation denatures the bacterial enzymes that can autolyze the cells of bacteria, therefore, to inhibit this there is a need to heat fix the smear. The heat fixation also enhance the attachment between the bacteria and the glass of slide so by which one can witness the smear clearly under the microscope.
Apart from these, there are some factors, which can result in poor results. Like when mixing bacteria with water, if one overmix, it can lead to inaccurate cell patterns. At the time of heat fixing, if one hold the slide over the flame for long duration, one would incinerate the cells.
Thus, heat fixing is important for the proper attachment of the bacterial cells with the slide and for proper visibility of the smear. One should also be careful about the factors, which may lead to poor results.
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In an experiment, a scientist decides to study the effect of exercise on cholesterol levels in people. He studies two set of people—those who exercise every day for an hour and those who don’t exercise at all. In this case, the statement that people who exercise for an hour may have lower cholesterol levels is .........
. To test this statement, the scientist would measure cholesterol levels in exercisers and non-exercisers. The cholesterol levels would be ........
.
In the mentioned case, the statement that the people who has the exercise for an hour may have lower levels of the cholesterol has the hypothesis, and the cholesterol levels in the experiment would be the dependent variable.
What is hypothesis?A hypothesis has the suggested statement, that has been based upon the previous information, and has been used as an initiation point in the scientific investigation.
Any scientific experiments that comprise two variables, that it has dependent and the independent variables. The independent variable that refers to the variable, which has controlled or the modified in the scientific experiment in order to determine the influence on the dependent variable.
Scientific hypotheses, in the general, are the premises within the given theory, which can be the validated on the basis of the scientific method, contributing to the formulation of the new hypotheses.
Therefore, the cholesterol levels would be a dependent variable.
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Several scientists from different countries are asked to examine the results of an experiment before a journal will print it.
Which term best describes this step of the investigative process?
question
communication of results
peer review
experiment control
Answer:
peer review
Explanation:
In science, results or findings from an experiment are usually published in journals. However, before they can be published, they have to undergo series of confirmation. One way to do this is to have several other scientists examine the results before finally publishing it. This is called PEER REVIEW.
PEER REVIEW is the process whereby an article that is about to be published in a scholarly journal is reviewed by researchers or scientists from the same field of study as the original scientist in order to ascertain the quality and validity of the result or findings. A peer-reviewed article is deemed to be of a very high quality.
Answer:
C. Peer review
Explanation:
I did the test
Sensory cells for hearing are located in the:______.
Answer:
cochlea
Explanation:
If you have a loss of antigen what happen to your body
Answer:
you would get sick time and time again
The angle subtended by stars in the night sky is orders of magnitude smaller than the acuity threshold you calculated in 1). Why are we able to see objects that are much smaller than the angle subtended by the gap in the acuity threshold experiment? (50 word max)
Answer is given below
Explanation:
we consider here gap in character size is 0.75 mm
and distance is 300 mm
so minutes of arc is = 0.85944
and
visual acuity is express as
V = standard view distance D ÷ distance at which each letter D' ................1
There is visual acuity under the eyes, on which the object cannot be determined Factor factor mainly determines refractive error and contrast angle brightness or brightness and duration of contrast and exposure The target resolution threshold is expressed as a small angle, which can reduce the distinction between important elements of the stimulus pattern such as a pair of dots. Relaxation is specified in terms of its angular sizeThis macromolecule (large) is used to carry genetic information. It's building block is called a nucleotide.
Explanation:
Nucleic acids are long chainlike molecules composed of a series of nearly identical building blocks called nucleotides. Each nucleotide consists of a nitrogen-containing aromatic base attached to a pentose (five-carbon) sugar, which is in turn attached to a phosphate group.
Which of the following accurately explains what it means to have a high specific heat ?
Answer:
This question lacks options; the options are:
A) Less heat is needed to keep water at a high temperature
B) Water efficiently absorbs and retains heat.
C) Heat is quickly released from water.
D) Water maintains a constant temperature
The answer is B.) Water efficiently absorbs and retains heat
Explanation:
A substance's specific heat refers to the quantity of heat the substance needs to increase its temperature by 1°C. Hence, a substance is said to have a high specific heat if it takes more heat energy to make it hot while a substance is said to have a low specific heat if it takes less heat energy to make it hot.
According to the question, water is being referred to. Water has a high specific heat meaning that it is good absorber of heat and retain it due to its hydrogen bonding. This is why water will take a longer time and high heat to increase its temperature because it absorbs and retains the heat supplied to it.
Which of these statements is the most complete definition of ecology? A.The study of the interactions between organisms in terms of competition and predation B.The study of the environment, in particular how to preserve it C. The study of the interactions between organisms and their environment D.The study of the environment, in particular how to save endangered species
Answer:
c I think I'm not sure tho
Which eukaryotic organelle was thought that have evolved from symbiotic bacteria? Describe how this event took place.
Answer:
The hypothesis that eukaryotic cells evolved from a symbiotic association of prokaryotes—endosymbiosis—is particularly well supported by studies of mitochondria and chloroplasts, which are thought to have evolved from bacteria living in large cells.
11.What element is the of life?
Answer:
Cells.
Explanation:
Because this question is so vague, there can be multiple different answers. However, when thinking about biology, we know that cells are the basic unit of life, considering the cell theory. The cell theory talks about how cells are the element of life because all living things are made of cells. They are the foundation of life on earth and without them, living things could not exist.
Some snakes produce a powerful poison that paralyzes their prey. This poison is an example of
Group of answer choices
an adaptation
resistance
an abiotic factor
a reptile
Answer:
This poisonis an example of an aboitic factor
The poison is an adaptation, as it is an advantage acquired through natural selection that allows the the snakes to bring down and capture their prey. Therefore, option (A) is correct.
What is adaptation?In biology, there are three related definitions of adaptation. First, natural selection, a dynamic evolutionary process, adapts organisms to their environments, improving their evolutionary fitness. Second, it is a condition that the populace has attained along that process. Thirdly, it is a phenotypic characteristic or adaptive trait that has been preserved and has developed via natural selection and has a functional purpose in each individual organism.
One example of physiological adaptation is the poison a cobra snake produces to defend itself against bigger creatures. They catch their victim using the poison as well.
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Where are semilunar valves to be found in a mammalian heart?
Answer:
at the base of the aortic and Pulmonary trunk
Explanation:
Structurally the mammalian heart is made up of blood vessels for the empty of the blood from the heart chambers -the ventricles. Due to the forceful contraction of the blood against gravity into theses vessels,there are tendency for the back flow, from the vessels back into the ventricles.
These may lead to mixing of deoxyganted with oxygenated blood.
Aorta is the largest artery in the heart.It takes oxygenated blood from the heart into the systemic circulations.To prevent the back flow of the pumped blood after the L.ventricular systole,layers of valves shut up,and stop the flow of blood back into the ventricles.. These are the semilunar vlaves at the bases of the Aorta. The sound produced by this shutting up is called the dupp sound.
Likewise deoxygenated blood flow into the pulmonary circulation en-route the lungs is transported by the Pulmonary trunks.Therefore to prevent the back flow of the deoxygenated blood back into the pulmonary trunk, thes semilunars valves are closed,after R. ventricular systole
These two valves ensures that R and L Ventricular contraction for the ejection of oxygentated and deoxygented blood occurs without backlow and therefore no mixing of the two types occurs.
4. Why are the results of the survey most likely unreliable?
Answer:
See the answer below
Explanation:
The results of surveys are most likely unreliable because surveys generally deal with questions that require value judgements or reporting beliefs. Consequently, there is no way to ascertain the objectiveness of responders and in most cases, responses are often biased.
Most survey questions are themselves inherently biased and only honest responses can make their results to be reliable. Unfortunately, there is no way to determine the veracity of responses. However, the unreliability of surveys reduces as the number of responders to the survey increases.
a.
Describe role and use of oxygen in air and life of animais
Answer:
All living organisms except plants need oxygen, as oxygen is what ignites all living things .. Plants take carbon dioxide and produce oxygen gas through the process of photosynthesis.
Answer:
Oxygen plays a critical role in respiration, the energy-producing chemistry that drives the metabolisms of most living things. We humans, along with many other creatures, need oxygen in the air we breathe to stay alive. Oxygen is generated during photosynthesis by plants and many types of microbes.
Give two examples of a deuterostome and two examples of a protostome.
Answer:
Protostomes: mollusks such as bivalves or gastropods.
arthropods such as crustaceans or insects.
Deuterostomes: echinoderms such as the starfish
hemichordates such as Enteropneusta (marine
vermiculated animals)
Explanation:
The embryonary development of bilateral coelom animals makes a place for the division of two groups: protostomes and deuterostomes. Among protostomes might be mentioned the flatworms, annelids, mollusks, and arthropods. Deuterostomes include echinoderms and chordates, among others.
These two groups differ in their specific development. Protostomes show spiral initial segmentation, and the mouth develops as a first opening near the blastopore. Deuterostomes show radial segmentation, the anus develops near the blastopore and the mouth develops later in another place.
How do plates move relative to each other at convergent plate boundaries?
Answer:
The movement of the plates creates three types of tectonic boundaries: convergent, where plates move into one another; divergent, where plates move apart and transform, where plates move sideways in relation to each other.
Explanation:
