Which of the following is true of crossing over? It involves the exchange of chromosome segments between homologous chromosomes. It occurs in meiosis I. It increases genetic variability. All of the choices are correct.

Answers

Answer 1

Answer: All of the choices are correct.

Explanation:

Meiosis is a type of cell division of the nucleus that occurs in cells that will give rise to gametes (egg or sperm). These are haploid cells (n), that is, they possess only one chromosome of each of the pairs (23 in total). Through meiosis from a diploid cell (2n), four haploid cells are obtained, thanks to two successive divisions called meiosis I and meiosis II.  Both comprise prophase, metaphase,  anaphase and telophase.

Homologous chromosomes are a pair composed of a paternal and a maternal chromosome. They have the same DNA sequence arrangement from one end to the other, but different alleles. These chromosome copies have the same genes at the same loci where they contribute tips along each chromosome that facilitate a pair of chromosomes to align correctly with each other before they separate during meiosis. Sister chromatids are those that make up a chromosome after duplication of the genetic material.  

The homologous chromosomes of maternal and paternal origin, mate and this process is called "synapsis" and form what is known as a tetrad or bivalent chromosome, giving the impression that it is a chromosome with four chromatids. In these tetrads, junctions called chiasmata are formed, areas in which both homologues exchange genetic material or genes, a process known as crossing-over. The chiasmata allow the chromosomes to be held together until their separation in anaphase l. So, genetic recombination is the process by which a segment of genetic material from a maternal chromosome is cut and then joined to a paternal chromosome (or vice versa) during prophase I of meiosis. So it happens between non-sister chromatids of a paternal and a maternal chromosome.

After crossing over, the homologous chromosomes are arranged randomly at the cell's  the equator of the cell at random (methaphase), facing each other, still united in the areas where crossing over occurred. Each chromosome is associated with a meiotic spindle fiber of the meiotic spindle and they are pulled along the meiotic spindle and driven toward the respective poles (anaphase). The chromosomes are now arranged at the poles and the reorganization of the nuclear envelope and the nucleolus begins. Finally, cytokinesis occurs and the rearrangement of cellular components and reorganization of the cytoskeleton. As a result of meiosis I,  2 haploid cells are obtained and then meiosis II occurs, where the sister chromatids are separated, generating two more cells (a total of 4).

Genetic variability is generated because the gametes produced during meiosis will not inherit the same chromosomes as the mother cell, but due to crossing over, the inherited chromosomes will be genetically different.


Related Questions

9.5 What are the similarities and differences between reproduction in amoeba and reproduction in hydra?​

Answers

Answer:

similarities: 1 they both reproduce asexually

Differences: 1 hydra reproduce through a process called budding whereas                              amoeba reproduce through a process called binary fission.

                    2 budding in hydra-  results in symetric division.

                       binary fission in amoeba- results in unsymetrical division.

Explanation:

Amoeba reproduces by a process known as binary fission in which parent cell divides into two equal daughter cells. Whereas in hydra reproduction occurs by budding. In budding, the bud is formed from the parent individual whereas in binary fission no bud formation occurs

Why might an individual with AIDS have difficulty fighting off otherwise harmless infections?​

Answers

Answer:

Having HIV/AIDS weakens your body's immune system. It destroys the white blood cells that fight infection. This puts you at risk for opportunistic infections (OIs). OIs are serious infections that take advantage of your weak immune system.

Explanation:

Which of the following is not a characteristic of pioneer species ?
They facilitate environmental change, making an environment more habitable for other species
They remain in an environment,even as more competitive species arrive
They tolerate a wide range of conditions
They are capable of colonizing a barren environment

Answers

Answer:

They remain in an environment,even as more competitive species arrive

Explanation:

Pioneer species, in ecological succession, are the first set of organisms to colonize a bare area of land or a disturbed area of land. Pioneer species include lichens, grasses, fungi etc.

Pioneer species have unique characteristics that distinguishes them from every other species of organism. These include:

- They facilitate environmental change, making an environment more habitable for other species.

- They tolerate a wide range of environmental conditions.

- They are capable of colonizing a barren environment, as in primary succession.

However, pioneer species do not remain in an environment, even as more competitive species arrive. They rather give way for new species to emerge and dominate.

Explain the importance of nitrogen-fixing bacteria?​

Answers

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Nitrogen-fixing bacteria fix atmospheric nitrogen to ammonia, which can then be taken up by plants.

The process is called biological nitrogen fixation.

Rhizobium, Azotobacter, cyanobacteria are some examples of nitrogen-fixing bacteria, which may be free-living or symbiotic.

The density of protists living in the hay infusion is ______________ than the regular pond water.

a. significantly lesser
b. lesser
c. about the same
d. greater
e. significantly greater

Answers

Answer:

a. significantly lesser

Explanation:

The density of protists living in the hay infusion is significantly lesser than the regular pond water because protists likes to live in aquatic or any water bodies. Some protists float on the surface of the water making their own food like plants by using the process of photosynthesis. Aquatic environments are ideal environment for protists, which have cilia and flagella that allows them to move in the water in search of food..

Match the organelle (1-4) with the correct description (5-8). 1) mitochondrion 5) synthesizing molecules 2) centriole 6) liquid in cell 3) endoplasmic reticulum 7) provides cell with energy 4) cytosol 8) aids the formation of the spindle apparatusA) 1 and 5, 2 and 6, 3 and 7, 4 and 8 B) 1 and 7, 2 and 6, 3 and 8, 4 and 5 C) 1 and 7, 2 and 8, 3 and 5, 4 and 6 D) 1 and 8,2 and 5, 3 and 6, 4 and7 E) 1 and 6, 2 and 8, 3 and 5, 4 and7

Answers

Answer:

C) 1 and 7, 2 and 8, 3 and 5, 4 and 6  

Explanation:

1 and 7: 1) mitochondrion; 7) provides the cell with energy

The mitochondrion is the organelle that produces the energy that the cell needs for its functions. It synthesizes adenosine triphosphate (ATP), which storages large quantities of energy in its bonds.

2 and 8: 2) centriole; 8) aids the formation of the spindle apparatus

The centrioles have a crucial role during mitosis. They form the spindle apparatus that attaches to the chromosomes, moving them to the opposite poles of the cell.

3 and 5: 3) endoplasmic reticulum; 5) synthesizing molecules

The endoplasmatic reticulum is a continuous membrane connected to the nuclear membrane. There are two types, the Rough Endoplasmatic Reticulum (RER) and the Smooth Endoplasmatic Reticulum (SER). The first one synthesizes proteins, while the second one synthesizes lipids.

4 and 6: 4) cytosol; 6) liquid in the cell

The cytosol is the liquid that is inside the cell. It is mostly water, but it also has ions and molecules. It is important for the transport of substances.

The correct match between organelles and their description is - Option C.  1 and 7, 2 and 8, 3 and 5, 4 and 6.

In the cell, there are many organelles that perform different and specific functions essential for the cell to survive. These organelles help in synthesizing molecules, energy production, cell division, and many others.

Mitochondrion: it is a cell organelle that is the site of cellular respiration, which is a process that breaks the sugar molecule and releases a high amount of energy in the form of ATP. Therefore, it is known as the powerhouse of the cell. Thus, correctly matches with 7) provides the cell with energyCentriole: It is organelles that help to form the spindle during the cell division in the cell that makes the region at the poles where spindle fibers form. Thus, it correctly matches with 8) aids the formation of the spindle apparatus.Endoplasmic reticulum: It is organelles that synthesize various molecules such as hormones and other protein molecules, Rough ER has ribosomes attached to it that synthesize proteins. Thus, correctly matches with 5) synthesizing moleculesCytosol: It is a semi-fluid-like substance made up of a lot of water, dissolved ions, smaller minute molecules, and proteins. It has filled in the interior cellular space. Thus, the correctly matches with 6) liquid in the cell.

Thus, the correct answer is - Option C.

Learn more about cell organelles:

https://brainly.com/question/17994377

If two haploid sperm fertilize a single haploid ovum, the resulting zygote would be considered a ________.

Answers

the answer:
triploid

What is socialization​

Answers

As this question as biology at the top,socialization is a social process with strong biological components that interact with social and cultural frameworks and factors

what are the qualities of woollen fabric that makes it suitable for winter​

Answers

Answer:

Heat conductivity

Explanation:When wool fibres are exposed to heat, moisture, and strain, they interlock and contract. Felting is aided by the scale-like exterior of the fibres. Heat conductivity: Since wool fibre is a weak conductor of heat, fabrics made from it are best suited for winter wear

Can bats eat butterflies?

Answers

Bat can eat butterflies, like most bugs. That being said they usually don’t eat butterflies as they are active at different times of the day then bats. Bat usually eat other bugs, such as moths, caterpillars, spider etc.

Hope this helps. Please consider making me the Brainliest, it’s not necessary but it is appreciated as I put time and research into each answer. Have a great day, stay safe and stay healthy.

walking, running and carrying a book involve using ________ type of muscles.
a) cardiac
b)voluntary
c)involuntary
d)Striated​

Answers

Answer:

It is voluntary I believe.

Explanation:

ments
Assignment 1 - Provide a narrative for the following scenarios. Use complete
sentences and be careful with spelling and grammar. 20 Points (5 points each)
1. The physician orders urine C&S on a patient. The patient asks why it is
necessary to do this test. How would you, the medical assistant, clearly
explain this to the patient?
2. A patient is asked to bring in a first morning urine specimen for testing.
You, the medical assistant, provide the patient with a container for the
collection and explain that it needs to be refrigerated if they cannot bring
it to the office right away. How do you explain to the patient the need
for a first morning specimen and the request to refrigerate?
3. A patient is being treated for diabetes. This patient asks you, the
medical assistant, why it is necessary a urine specimen is collected each

Answers

Answer:

1.Urine culture and sensitive is used to identify the microorganism that is causing the infection, and to identify the antibiotics, sensitive to the microorganism, if the urinary tract is not treated promptly it can lead to recurrent urinary tract infection.

2. First urine sample of the morning is more concentrated form as urine is present in the bladder for almost 8 hours. It contains an increased number of protein or urinary casts. The sample is placed in the refrigerator to get refrigerated as holding it at room temperature and if infected with bacteria present in the urine it uses the glucose and alter the results.

3. diabetic ketoacidosis is one of the many complications if you are having diabetes. Another complication is diabetic nephropathy inorder to check the urine acetone as well as protein in urine we advise for urinalysis each time you visit.

When the belt is moving at a high speed, 350 pills can be coated per hour. How many minutes would it take to coat all the pills in this batch at a high speed?

Answers

Answer:

6 pills are coated in one minute time.

Explanation:

There are 350 pills can be coated in 60 minutes due to high speed of belt movement which means that 6 pills are coated in one minute time period so if there are 60 pills so the belt takes 10 minutes to complete the coating of the pills. If there are 200 pills to be coated then we used the equation i.e.

6 pills -------- 1 minute

200 -------- x

By cross multiplication we get,

6x = 200 x 1

x = 200 / 6

x = 33.3 minutes

This means that in 33 minutes the belt can coated 200 pills.

Please help me with question 7 ASAP

Answers

Answer:

B is the correct answer.

Explanation:

A is incorrect because diffusion does not depend on living system. It can occur in non-living systems as well. C is incorrect because when all transport proteins are used, the transported molecules are carried by the maximal number of transporters. Thus, the transport rate of substance is maximal.

D is false because translocation is primarily related to phloem.

Hemophilia is inherited in humans as an X-linked recessive condition. A phenotypically normal woman whose father was hemophiliac marries a normal man. What is expected among their offspring?

Answers

Answer:

100% of the girls are expected to be normal, X+X+ and X+X-50% of the boys are expected to be normal, X+Y50% of the boys are expected to be hemophilic, X-Y75% of the whole offspring normal (X+X+, X+X-, X+Y)25% of the whole offspring hemophilic (X-Y)

Explanation:

Due to technical problems, you will find the complete explanation in the attached files

It was found that the C4 protein promotes synaptic pruning during brain development in the teenage years. This is a normal process in brain development that is important for removing unnecessary connections between neurons and establishing a mature brain structure. However, high expression levels of a certain allele of C4 can lead to too much pruning, which may promote the onset of schizophrenia. The variation observed at the C4 gene which leads to the greatest increase in risk was found to cause a 25% increase in the risk of developing schizophrenia. The baseline risk in the population is 1%. What is the risk of an individual with this variant developing the condition?a. 0.25%.
b. 1.25%.
c. 25%.
d. 26%.

Answers

Answer:

b. 1.25%

Explanation:

Variations observed in C gene has increase in risk of 25% to develop schizophrenia. It is a kind of an abnormality in which a person interprets reality unrepresentative. The baseline risk in population is 1% then there is 1.25% risk associated with an individual to develop this condition.

g Cerebrospinal fluid formed in the lateral ventricles travels through the ________ to reach the third ventricle.

Answers

Answer: Interventricular foramen

Explanation:

The cerebrospinal fluid is a fluid that covers the brain and spinal cord. It circulates through the subarachnoid space, the cerebral ventricles and the ependymal canal. Several diseases alter its composition and its study usually detects meningeal infections, carcinomatosis and hemorrhages. Some of its functions are:

Hydropneumatic support against local pressure for the encephalon.Eliminates metabolites from the central nervous system.Protects the central nervous system from trauma.

This fluid also fills the ventricles, which are large open structures deep within the brain and help keep the brain buoyant and cushioned. The lateral ventricles are the largest ventricles and connect to the third ventricle through the intraventricular foramen. This third ventricle is a narrow, medial cavity located between the diencephalic masses. Then, the interventricular foramina are channels that connect with the ventricles of the lateral walls and with the third ventricle, at the level of the midline of the brain. Like these channels, they allow cerebrospinal fluid to circulate through the rest of the ventricular system of the brain. The walls of the foramina also contain choroid plexuses, responsible for the production of cerebrospinal fluid, which continue in both the lateral ventricles and the third ventricle. After reaching the third ventricle, the cerebrospinal fluid travels through the median aperture into the subarachnoid space at the base of the brain.

What is the role of an indicator? Predict how the glucose test strips and iodine would react with the following foods:

Grape
Tomato
Summer squash
Orange
Bell pepper

Answers

Answer:

Tomato

Explanation:

Pleasssee helepppppp

Answers

THE NASAL CAVITY IS A HOLLOW SPACE WITHIN THE NOSE AND SKULL THAT IS LINED WITH HAIRS AND MUCUS. THE FUNCTION INTO WARM, MOISTURIZE, AND FILTER AIR ENTERING THE BODY BEFORE IT REACHES THE LUNGS

If the complex cholesterol- HRP would not be commercially available, use the knowledge you learnt and internet to determine an alternative way for detecting cholesterol.

Answers

Answer:

Classical chemical methods, enzymatic assays, gas chromatography (GC), liquid chromatography (LC), and mass spectrometry (MS)

Explanation:

Classical chemical methods, enzymatic assays, gas chromatography (GC), liquid chromatography (LC), and mass spectrometry (MS) are the alternate methods used for the detection of cholesterol. These methods are used when HRP would not be commercially available for the analysis or detection of cholesterol in the patient's body so these methods can be used for the purpose of detection of cholesterol.

Antibacterial sprays are often used when cleaning kitchen counter tops. If the same antibacterial spray is used continuously, why will some bacteria survive and reproduce?

A) Bacteria have developed resistance to the spray
B)The spray only prevents the bacteria from multiplying.
C)New species of bacteria are formed when the spray is used.
D)Most of the sprays are designed to kill only one type of bacteria.

Answers

Answer:

A

Explanation:

D) most of the sprays are designed to kill only one type of bacteria

Dalits are followed enters in temples true or false

Answers

Answer:

False A notice by the priest told dalits they can’t enter the temple because they are “not pure”

examples of c3 and c4 plants​

Answers

C3 vs C4 Plants
C3 Plants C4 Plants
Examples include rice, wheat, oats, barley, cotton, peanuts, tobacco, sugar beets, soybeans and spinach Examples include Maize, Sugarcane, pearl millet, sorghum.
Leaves of these plants DO NOT show Kranz anatomy. Leaves of these plants show Kranz anatomy.

which molecule is a saturated fat?

Answers

Answer:

Option B is the correct option

After mitosis, the number of chromosomes is ______ as/of the parent cell.

After meiosis, the number of chromosomes is _____ as/of the parent cell.

Answers

Answer:

meiosis 4

mitosis 2

Explanation:

Answer:

For mitosis - the same

The number of chromosomes at the end of mitosis are [THE SAME] as the parent cell.

________________

For meiosis - half

The number of chromosomes at the end of meiosis are [HALF] as much as the parent cell.

Explanation:

Trust me, this is correct. Tried it myself.

( PLEASE ANSWER IT FAST) Label the Organelles of a Cell
Identify the organelles in the cell to the right.

Answers

i think i'm too late to help D:

Answer:

A-vacuole

b- chloroplast

c-cell membrane

d- golgi

e- endoplasmic

f-cell wall

Explanation:

Which is not true regarding the mammalian cardiac cycle

Group of answer choices

both atria contract at roughly the same time, and then the ventricles

relaxation, or filling, phase is called diastole

the semilunar valve is the usual pacemaker

contraction, or pumping, phase is called systole

Answers

the semilunar valve is usual peacemaker

Besides oxygen exchange, the respiratory system also functions to eliminate (Click to select) . Too much of this gas can cause a(n) (Click to select) in blood pH, compromising homeostasis.

Answers

Answer: Carbon dioxide, decrease

Explanation:

Cellular respiration is a set of reactions by which organic compounds (sugars) are degraded by oxidation to inorganic substances. This process provides energy in the form of ATP and to achieve this, many reactions occur in which electrons are passed from one molecule to another, called redox reactions. In the case of aerobic respiration, the final electron acceptor is molecular oxygen, which is reduced to water.  Oxygen, like any gas, crosses the plasma membrane and then the mitochondrial membrane, and in the mitochondrial matrix it binds electrons and protons, forming water. It is in this final oxidation and in previous processes that energy is obtained. The reactions that extract energy from sugars such as glucose are catabolic reactions since a large molecule is broken into smaller molecules. For example, when glucose is broken down in the presence of oxygen, six molecules of carbon dioxide (CO2) and six molecules of water are obtained. Both CO2 and water are eliminated by lung exhalation.

In the event that this carbon dioxide is not completely eliminated, something called respiratory acidosis occurs, which is one of the disorders of the acid-base balance due to a decrease in the frequency of respirations or hypoventilation. The increase in the concentration of carbon dioxide in the blood causes the pH value to decrease. This scale is a measure of the degree of acidity or alkalinity of a substance or solution. A pH value of less than 7 means it is more acidic, and a pH value of more than 7 means it is more alkaline. Carbon dioxide is constantly produced as the body metabolizes energy, which will accumulate in the circulation rapidly if the lungs do not remove it properly. Alveolar hypoventilation thus leads to an increase in arterial CO2 partial pressure. The increase in pressure in turn decreases the ratio of bicarbonate (HCO3) to bicarbonate pressure with a consequent increase in acidity or decrease in blood pH. The body's metabolism rapidly generates a large amount of carbonic acid (H2CO3) and non-volatile acid. The lungs normally excrete the volatile fraction through ventilation without accumulation of acid in the blood but in this case this is not possible and this accumulation of carbonic acid causes the pH to rise. This disrupts homeostasis, a form of equilibrium that is achieved through a network of feedback control systems that constitute the self-regulatory mechanisms.

What process in biology requires energy from a cell?

Answers

Answer:

I would assume you are talking about just basic general biology, in which case it's probably just looking for cellular respiration.

Explanation:

Metabolism is a combination of chemical reactions that are spontaneous and release energy and chemical reactions that are non-spontaneous and require energy in order to proceed. Living organisms must take in energy via food, nutrients, or sunlight in order to carry out cellular processes.

WILL MAKE BRAINLIEST

Fill in the blank below with the word that best completes the sentence.
Natural selection leads to____
a process of change in a population over time.

Answers

Answer:

it is evolution

hope it helps

the answer is evolution
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