Answer:
A) A molecular clock is a measure of evolutionary time based on the theory that specific DNA sequences mutate at constant rates. To use a molecular clock, scientists first select two different species and compare their DNA sequences. They can compare the DNA sequences directly, or by looking at the RNA and protein molecules created from the DNA. Molecular clocks help to measure the number of changes and mutations which accumulate in the gene sequence of different species over a period of time.
B) Molecular clocks assume the neutrality of gene mutation. They are based on the fact that genetic mutations although random, occur at a relatively constant rate. Evolutionary biologists use this information to deduce how species evolve and determine when two species diverged on the evolutionary time line. It is useful in the study of variations in selective forces, and also facilitates establishing the dates of phylogenetic events including those not documented by fossils. Molecular clocks do have some limitations. Rates of change may not be constant, may not be the same in all organisms, and may be different for different genes.
I used the answer above and added some stuff here and there, so credit to them. I'm not sure if what I wrote makes much sense, but hopefully it can be somewhat helpful. :)
why is reproductive isolation insufficient to define a species?
A. This definition overlooks artificial preproduction, such as in zoos
B. Reproductive isolation doesn't take outgroups into account
C. This definition excludes organisms that reproduce asexually
D. Reproductive isolation can be accomplished in a variety of ways
The correct option is (c) This definition excludes organisms that reproduce asexually.
Asexual reproduction is also possible in bacteria, yeast, fungi, plants, and other organisms. Most frequently, yeast proliferate by budding. Plants and fungi both use spores for asexual reproduction. Additionally, plants are capable of reproducing asexually by vegetative propagation.Numerous eukaryotic creatures, such as plants, animals, and fungus, are also capable of asexual reproduction. Parthenogenesis, the most prevalent type of asexual reproduction in vertebrates, is frequently employed as an alternative to sexual reproduction when sexual reproduction isn't an option.What are the 4 types of asexual reproduction?Asexual reproduction includes fission, budding, fragmentation, and parthenogenesis, while sexual reproduction is achieved through the combination of reproductive cells from two individuals.
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1 pe If a fox has 15 pairs of chromosomes in it's lung cell , how many total chromosomes are in it's eye cell? (type the number only) * Your answer
El mundo comas en el oya, pedthon el numbaras.
Pearl the whale had a horrible accident at cheerleading practice and needed a blood transfusion. So she needed to find out her possible blood type. Her dad, Mr. Krabbs is heterozygous for blood type A and her mom is heterozygous for blood type B. Make a Punnett square to show Pearl’s possible blood type(s). Mr. Krabbs genotype: ________ Mrs. Krabbs genotype: ________ What is the possibility of Pearl having blood type O? ____ What is the possibility of Pearl having blood type AB? ____ What is the possibility of Pearl having blood type A? ____ What is the possibility of Pearl having blood type B? ____ - Is this scenario an example or incomplete dominance or codominance? Explain. - How can some people receive O-type blood which is recessive?
Answer:
Mr Krabs genotype: A0
Mrs K= B0
Possible genotypes: AB, B0, A0, 00
The possibility that pearl has blood type O is 25%, type A 25%, type B 25%
this scenario is an example of codominance
B. Population Dynamics Symbiotic Relationships
Ticks
Ticks belong to a family called Acarina, which also contains mites. Ticks eat by taking blood from
other organisms such as wallabies, lizards, echidnas and occasionally humans. In humans this can
lead to symptoms such as itching, head aches and in extreme cases flu like symptoms, facial
paralysis, and meat allergy.
1. Identify the relationship a tick has with its host. Justify your answer [3]
Answer:
Parasitism
Explanation:
Parasitism is a form of relationship in which one of the organism is being harmed while the other benefits. The organism being harmed is usually called the HOST while the organism that benefits is called PARASITE. Parasites often inflict certain health-related conditions on their hosts.
According to this question describing the mode of feeding of ticks, they are said to eat by taking blood from other organisms such as wallabies, lizards, echidnas and occasionally humans, which are all HOSTS.
In human hosts, this relationship with ticks can lead to symptoms such as itching, head aches and in extreme cases flu like symptoms, facial paralysis, and meat allergy etc. From the description above, it is clear that TICK has a PARASITIC RELATIONSHIP with its host as it brings only harm to them and benefits itself.
When we consider the motion of particles such as the molecules that comprise air, which of the following is False?
Group of answer choices
Molecules move in a random motion and will collide with other particles or a container
As temperature increases, there is an increase in molecular motion
Molecules move from areas of high concentration to areas of lower concentration
As temperature decreases, there is an increase in molecular motion
Answer:
D
Explanation:
If you see two contradictory answers (B & D), one has to be the choice. As temperature increases, molecular motion decreases is false. Diffusion is what choice C is describing and is true.
Which of the following molecules comes from the food we eat and is needed for energy?
A) amino acids
B) glucose
C) oxygen
D) protein
E) fiber
A chemical reaction is shown.
SnO2 + H2 → Sn + H2O
What is true about this chemical reaction?
A.
It is balanced because the mass of the reactants (number of atoms) is equal to the mass of the products (number of atoms).
B.
It is unbalanced because the mass of the reactants (number of atoms) is greater than the mass of the products (number of atoms).
C.
It is unbalanced because the mass of the reactants (number of atoms) is less than the mass of the products (number of atoms).
D.
It is balanced because the number of reactants (number of atoms) is equal to the number of products (number of atoms).
Read the information about an experiment.
Jadon plans on carrying out an experiment involving the burning of steel wool to illustrate the conservation of mass. Steel wool is made of iron. When it is burned it combines with oxygen to form iron(III) oxide.
Which step in his experiment is the most important if he wants his experiment to correctly demonstrate the conservation of mass?
A.
The steel wool should be burned inside of a sealed jar or other closed system.
B.
The steel wool should be burned over a long period of time (at least two hours).
C.
The steel wool should be burned in a room that is at room temperature (20–25°C).
D.
The steel wool should be burned in its entirety sExpected Outcomes – Metals in Hydrochloric Acid
Metal Observations
Copper No reaction even when gently heated
Iron Little initial reaction.
More vigorous reaction when heated.
Positive test for hydrogen gas.
Solution turned from colorless to yellow.
Magnesium Vigorous initial reaction; rapid evolution of gas.
Positive test for hydrogen gas.
All of the magnesium seemed to disappear.
Solution remained colorless.
Zinc Initial reaction produced rapid evolution of gas; less vigorous than magnesium.
All of the zinc seemed to disappear.
Solution remained colorless.
Students in Ms. Brown's Science Lab demonstrated several chemical reactions, by placing the each above chemicals in HCl (hydrochloric acid). Unfortunately, the data did not appear to support the Law of Conservation of Matter in any of the experiments. The recorded Mass of the Reactants did not match the Mass of the Products. Based on the expected outcomes listed in the table above, what might be a reason that their demonstrations were not successful?
A.
They only used metals
B.
They perfomed the experiment in a closed system
C.
The experiment was not performed in a closed system
D.
They didn't use enough HCl that no iron is left in its original state.
Answer:
1) A chemical reaction is shown.
SnO2 + H2 → Sn + H2O
What is true about this chemical reaction?
B.
It is unbalanced because the mass of the reactants (number of atoms) is greater than the mass of the products (number of atoms).
2) Read the information about an experiment.
Jadon plans on carrying out an experiment involving the burning of steel wool to illustrate the conservation of mass. Steel wool is made of iron. When it is burned it combines with oxygen to form iron(III) oxide.
Which step in his experiment is the most important if he wants his experiment to correctly demonstrate the conservation of mass?
A.
The steel wool should be burned inside of a sealed jar or other closed system.
Explanation:
The explanation to number 1 is that I selected it in my test and got it.
The explanation the number 2 is from the link below:
https://quizizz.com/admin/quiz/5dee60258f1145001bc02ed5/physical-science-2nd-9-weeks-practice-test-2020
The true statement about the given chemical reaction is-It is balanced because the mass of the reactants (number of atoms) is equal to the mass of the products (number of atoms). Therefore, the correct options for all the problems are 1-A, 2-A and 3-D.
What is a balanced equation?A balanced equation refers to an equation where the number of atoms of each element is the same on both sides of the equation. The given equation is balanced because the number of Sn atoms and the number of H atoms on the reactant side are equal to the number of Sn atoms and the number of H atoms on the product side.
1. The steel wool should be burned inside a sealed jar or other closed system is the most important step if he wants his experiment to correctly demonstrate the conservation of mass.
2. They didn't use enough HCl that no iron is left in its original state might be a reason that their demonstrations were not successful.
Therefore, the correct options are 1-A, 2-A and 3-D.
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Which symbol represents a hybrid?
Aa
dE
BB
cc
Answer:
I think its Aa
Explanation:
Not very good at biology :/
I will mark brainiest for correct answer
A pelican has a dip netting beak. How does it eat?
A. It traps fish between its upper and lower mandible much like a scissor,
B. It takes a big gulp of water with fish and filters the water off of the fish before swallowing,
C. It opens holes in trees and eats insects beneath the surface of the wood,
D. It burrows in the mud to find insects and other small invertebrates beneath the surface
Answer:
b is correct
Explanation:
Answer:
b they scoop them and then drain the water a swallow all remaining animals
1.) A person walks 12.5 km in 1.9 h. What is the person's
average velocity in km/h and m/s?
Answer:
1. 6.56 km/hr
2. 1.83 m/s
Explanation:
The average velocity/speed can be calculated using the formula;
Average speed/velocity = distance/time
According to the information provided in the question, distance = 12.5km, time = 1.9h
Average velocity in km/hr = 12.5/1.9
= 6.578
= 6.56km/hr
However, in order to calculate the average speed in m/s, we have to convert distance in km to m, and time in hour to seconds.
1km = 1000m
12.5km = 12.5 × 1000
= 12500m
1 hour = 3600seconds
1.9hours = 1.9 × 3600
= 6840seconds
Average velocity = 12500/6840
= 1.827
= 1.83m/s
A segment of mRNA has the sequence UGACAUAGC. Which of the following would represent the
strand of DNA from which this piece of mRNA was made?
O ACTGTATCG
O ACUGUAUCG
O CGAUACAGU
O GTACAGATT
Answer:
B
Explanation:
U(uracil) pairs with A(adenine), G(guanine) pairs with C(cytosine)
A newly identified virus infects a eukaryotic host cell without producing virions right away, with a long period where the host is largely unaffected by the infection. What's the best description of this virus?
A: This virus rapidly causes lysis of the host cell
B: This virus has a long period of latency
C: This virus is a bacteriophage
D: This virus can't replicate
The best description of the virus is that the virus cannot replicate. The correct option is D.
What is a virus?A virus is an infectious agent which is non-living normally, but it becomes alive when come in contact with any living cell. It causes many diseases in humans, animals, and plants.
Here, the virus is not producing virions, which means it doesn't cause lysis. It doesn't affect the host, so do not have a long period of latency, and is not a bacteriophage, so the virus is not replicating.
Thus, option D: This virus can't replicate is correct.
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What is the primary mechanism associated with the role of fluoride in prevention of dental caries? a. Fluoride increases calcium absorption, which increases crystal formation of teeth b. Fluoride increases salivation which aids in the removal of bacteria and the foods needed to sustain bacterial growth c. Decay is reduced due to the inhibitory effects of fluoride on growth of bacteria on the teeth d. Fluoride becomes incorporated into the crystalline structure of teeth, making them less susceptible to decay e. Decay is inhibited due to neutralization of organic acids produced by bacteria on the teeth
Answer:
d. Fluoride becomes incorporated into the crystalline structure of teeth, making them less susceptible to decay
Explanation:
Dental caries results when cariogenic (caries-causing) bacteria metabolize carbohydrates or sugars present in the mouth for their energy needs, producing organic acids as byproducts, thus lowering the pH of the plaque biofilm.
The hydroxyapatite of tooth enamel is composed mainly of phosphate ions (PO₄³⁻) and calcium ions (Ca⁺). Under normal conditions, there is a stable equilibrium between the calcium and phosphate ions in saliva and the crystalline hydroxyapatite. At low pH (acidic conditions), there is a shift in equilibrium resulting in the dissolution of hydroxyapatite from tooth enamel, a process known as demineralization. A reverse process called remineralization (the process of incorporation of minerals in tooth enamel) occurs when the saliva, acting as a buffer elevates pH. When equilibrium is shifted to favor continued demineralization, dental caries results.
However, when fluoride is present in saliva, fluorapatite, rather than hydroxyapatite, forms during the remineralization process as fluoride ions replace hydroxyl groups in the formation of the apatite crystal lattice.
Fluorapatite is less soluble than hydroxyapatite making it more resistant to demineralization, even under conditions of low pH. Thus, fluoride acts as an effective anticaries agent.
Help is much needed please, thank you?
Answer:
I belive the answer is #3
Explanation:
what is a example of acceleration?
Answer:
For example, if a car turns a corner at a constant speed, it is accelerating because its direction is changing. The quicker you turn, the greater the acceleration. So there is an acceleration when velocity changes either in magnitude or in direction, or both.
Explanation:
hope this helps... (i can't see the pic...)
(─‿─)
Clearly outline what differentiates Gram +ve bacteria from Gram -ve bacteria?
Answer:
Gram positive bacteria have cell walls composed of thick layers of peptidoglycan. Gram positive cells stain purple when subjected to a Gram stain procedure. Gram negative bacteria have cell walls with a thin layer of peptidoglycan.
4. What is a chromosome?
Plastics like PVC pipe and Teflon used to make non-stick cooking trays are made by bonding large chains of carbon molecules to other molecules; disrupting Earth's natural cycles. How is the use of plastics disrupting nature? A) Production uses 10% of Earth's energy. B) Animals/Fish can not digest the enzymes. C) Landfill's leak harmful chemicals into the atmosphere. D) Floating plastic waste serves as transportation devices for invasive species, disrupting habitats.
B) Animals/Fish can not digest the enzymes.
What is one of the chief alms of water conservation?
Answer:
gdk
and got tooka killed Explanation:
But if the male Himalayan rabbit's genotype is c(h)c, and it mates with an albino female whose genotype is cc isn't there a 25% chance that the offspring could be albino? and why can't you breed two Himalayan's together to get a Himalayan?
Answer: Go-ogle
Explanation: Is helpful
Please hurry!!!
How does the DNA change during meiosis?
Answer:
Scotland
Law is a surname, of English, Scottish, Cantonese, or Chinese origin. In Scotland, the surname means dweller at the low; as in a hill. Another origin of the surname is a contraction of Lawrence, or Lawson.
Explanation:
Answer:When recombination occurs during meiosis, the cell's homologous chromosomes line up extremely close to one another. Then, the DNA strand within each chromosome breaks in the exact same location, leaving two free ends. Each end then crosses over into the other chromosome and forms a connection called a chiasma.
Explanation: Np
Why are most systems in the human body negative feedback systems?
Most systems in the human body are negative feedback systems because negative feedback systems allow humans to regulate and stabilize their systems, which is the first option as a negative feedback system regulates the body's functioning.
What is the negative feedback system?Negative feedback is a regulatory mechanism in which a change in a physiological variable triggers a response that opposes the initial change, for example, in the regulation of body temperature, when the body becomes too hot, thermoreceptors in the skin and other tissues detect the change in temperature and send signals to the hypothalamus, which acts as the body's thermostat and as a feedback mechanism, hypothalamus triggers responses that cool the body, such as vasodilation to increase blood flow to the skin, sweating to release heat, etc.
Hence, most systems in the human body are negative feedback systems because negative feedback systems allow humans to regulate and stabilize their systems, which is the first option.
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Pairs of chromosomes contain (the same/different) types of genes.
Answer:
The 22 pairs of homologous chromosomes contain the same genes but code for different traits in their allelic forms since one was inherited from the mother and one from the father. So humans have two homologous chromosome sets in each cell, meaning humans are diploid organisms.
HOPE THIS HELPS
Choc
Fill in the blanks to complete these sentences about rock characteristics.
A rock is an
of minerals.
The
of a rock is a result of its mineral composition.
Most rocks contain more than one type of
Answer and Explanation:
A rock is an made of minerals??
The forming of a rock is a result of its mineral composition??
Most rocks contain more than one type of mineral??
Answer:A rock is an made of minerals??
The forming of a rock is a result of its mineral composition
Explanation:
how many sperms are formed in four primary spermatocyte
Which nucleic acid serves as a strand for protein synthesis?
a. tRNA
b. ribosome
c.mRNA
d.dATP
Answer:
c.mRNA...............
Someone please help ASAPPPP
Answer:
(its C)
if its right tell me!
HELP!!!
Part.2
This is science.
Answer:
snuflower (common) = Queen anne' s lace
Please help me!
Explain how some structures in the skin protect your body.
Which RNA molecule is matched with its correct function?
Answer:
Which class of RNA is correctly paired with its function? Transfer RNA (tRNA): attaches to an amino acid. What is the difference between the template strand and the nontemplate strand? The template strand is the DNA strand that is transcribed into an RNA molecule, whereas the nontemplate strand is not transcribed