What prevents blood from circulating backward in veins?
A.valves
B. capillaries
C. lungs
D. heart

Answers

Answer 1

Answer:

A.Valves

Explanation:

The pulmonary vein empties oxygen-rich blood from the lungs into the left atrium. As the atrium contracts, blood flows from your left atrium into your left ventricle through the open mitral valve. When the ventricle is full, the mitral valve shuts. This prevents blood from flowing backward into the atrium while the ventricle contracts.


Related Questions

Which structure does a virus have in common with a prokaryotic cell?
cell wall
O nucleic acid
ribosome
capsid

Answers

Answer:

Explanation:

cell-wall

the answer is capsid

प्र.नं. १ समूह'क' मा दिइएकोश

लेख्नुहोस् :

कञ्चन
तिरष्कार
आशा गरिएको
उपेक्षा
पहिलेदेखि चलिआएको
सन्नाटा विद्युतीयपत्रवा चिठी
अनलाइन
सुनसान
इन्टेरनटमा रही सूचनाआदानप्रदान गर्ने प्रविधि
रहस्यमय
नं.२ खाली ठाउँमा उपयक्तशब्दभर्नहोस ।
[tex]7788x \times \times 789[/tex]

Answers

plz attach photo .....

Explanation:

फोटो हाले बल्ला बुझिन्छ । यसरी त के के हो के के।।।।

मिल्छ भने क्रिपया फोटो राखेर प्रश्न न सोध्नु होला

question sodda photo rakhera sodnu vako vaye bujhna sajilo hunthiyo

Which pie graph is shaded to best represent the approximate percentage of time that humans have existed during Earth’s entire history?

Answers

Answer: I chose D and got it right just always choose the smallest one their hope this helps yall

Explanation:

Which form of natural selection does the graph represent

Answers

Answer: where's the graph?

Sample Food Chain
Leaf------> Caterpillar--------> Chameleon---------> Snake-----------> Mongoose

Looking at the above picture, what is true?

A) The Mongoose is the tertiary consumer
B) The chameleon eats the snake
C) The chameleon is an autotroph
D) If Mongoose is removed, snake population would increase.

Answers

Answer:

D

Explanation:

there will be no predators to eat the snakes

A state of economic scarcity exists when consumers:

Answers

Answer:

Scarcity exists when there is not enough resources to satisfy human wants. One of the most widely known examples of resource scarcity impacting the United States is that of oil. As global oil prices increase, local gas prices inevitably rise.

Explanation:

Farmer toon soon wanted to start breeding his plants so that they are resistant to disease while producing more fruit per plant.Which plants should the farmers cross to get the desired (wanted) combination of traits

Answers

Answer:

cultivated plant variety with its wild type variety.

Explanation:

The farmer cross the cultivated plant variety to its wild type which has the characteristics of resistance against diseases. Due to crossing, the offspring produce having resistance against that disease as well as producing high yield. This type of crossing is known as artificial selection in which humans cross two organisms to get the desired characteristics in their offspring so to get a plant with resistance against disease we cross cultivated plant variety to its wild type.

About 3 million years ago, the Isthmus of Panama (a narrow strip of land connecting North and South America) formed, dividing marine organisms into Pacific and Caribbean populations. Researchers have examined species of snapping shrimp on both sides of the isthmus. Based on the morphological species concept, there appeared to be seven pairs of species, with one species of each pair in the Pacific and the other in the Caribbean. The different species pairs live at somewhat different depths in the ocean. Using mitochondrial DNA sequences, the researchers estimated phylogenies and found that each of these species pairs, separated by the isthmus were indeed each other's closest relatives. The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other, and any that did mate almost never produced fertile offspring. Which process led to the formation of the species pairs of Pacific and Caribbean snapping shrimp

Answers

Answer:

Allopatric speciation

Explanation:

Allopatric speciation refers to the geographic separation of a continuous genetic background, originating two or more new geographically isolated groups. These divergences of the original population might be related to migration in different directions, extinction of geographically intermediate populations, or geological events. During these events of speciation, emerging new barriers impede genetic flow between groups, as the two new populations that are separated can not get together and mate anymore. These barriers might be geographical or ecological.  

Different stages are involved in the allopatric speciation process:

• The emergence of the barrier.  

• Interruption in the genetic flow

• Slow and gradual differentiation due to the occurrence of mutations in each population and their accumulation in time.  

• Genetic divergence by natural selection and reproductive isolation,  impeding the two groups to mate even if the barrier disappears.  

• Prezigotic isolation mechanisms favored by selection a secondary contact between the new species occurs.

The Panama isthmus is an example of allopatric speciation caused by an extrinsic geological barrier that interrupted the genetic flow between species driving to genetic changes and reproductive isolation.  

Two different groups that evolved in allopatry might meet again in secondary contact if the barrier that separated them, disappears. In the Panama isthmus example, the groups that did mate, could not produce any fertile progeny because of postzygotic reproductive isolation. And the groups that did not mate, were not attracted to each other because of prezygotic reproductive isolation.  

The image below shows plant cells. plant cells What feature of cells is best demonstrated in the image? A. Cells are formed from other cells within the same tissue. B. All organisms are made up of a large number of cells. C. All organisms have cells with different shapes and functions. D. Cells are the basic units of structure and make up tissues.

Answers

Answer:

The answer is C

Explanation:

I took the test

Which of the following is most likely to form when hot magma rises up as tectonic plates move apart below the ocean
1.mid-ocean ridge
2.fault
3.trenches
4.subduction zone

Answers

That would be the fault

Answer:

A. Mid-ocean Ridge.

Explanation:

A mid-ocean ridge a mid-oceanic ridges are underground mountain formed by tectonic plates.

Analyze the scatterplot graph.



Which trend does the graph show?

Answers

Answer:

Can you provide us with a picture of the graph?

Explanation:

No one can answer the question if we can't even see the graph you're asking about.

can anyone tell me what all books are there for cbse pcb class 11​

Answers

Answer:

NCERT Biology for Class 11.

NCERT Chemistry Part I for Class 11.

NCERT Chemistry Part II for Class 11.

NCERT Physics Part I for Class 11.

NCERT Physics Part II for Class 11.

NCERT Hornbill - English Core for Class 11.

NCERT Snapshot - Supplementary English Core for Class 11.

hope it helps

Small changes can add up over MULTIPLE GENERATIONS to make
A. the same species

B. new species

Answers

Answer:

b: new species

Explanation:

These changes are genetic mutations to their biological "code" meaning creating a new species would be possible.

Answer:

B. new species

Explanation:

Biological evolution is any change in the heritable traits within a population across generations.

The skull and vertebrae are part of the _________ in vertebrates. circulatory system endoskeleton nervous system exoskeleton Science

Answers

Answer:

Endoskeleton

Explanation:

Hope this helps!

Answer:

nerveos systum i think is tha anser

Which of the following correctly describes the arrangement of the phospholipids in the lipid bilayer of the cell membrane? *

Phospholipids line up head to head, so the phosphate heads are separated from water.
Phospholipids line up head to tail, because opposites attract.
Phospholipids line up tail to tail, so the fatty acid tails are separated from water.
Phospholipids line up with no pattern, because they're molecules which move randomly.

Answers

Answer:

Two layers of phospholipids where the outer layer has the hydrophilic heads facing toward the outside of the cell and the inner layer have the hydrophobic tails facing toward the inside of the cell.

PLEASE HELP! WILL MARK BRANLIEST!

Fill in the correct answers in the boxes below.

Answers

Answer:

The answers are as followed:

Explanation:

9: Non renewable

10: Organisms

11: Millions

Answer:

9. nonrenewable

10. I think it's plants?

11. millions of years

Explanation:

what happens directly after metaphase

Answers

Answer:The third phase of mitosis, following metaphase and preceding telophase, is anaphase. Since the sister chromatids began attaching to centrosomes on opposite ends of the cell in metaphase, they're prepped and ready to start separating and forming genetically-identical daughter chromosomes during anaphase.

Explanation:

Answer:

The next phase is anaphase. The chromatids separate at the centromere. The spindle fibers begin to pull them to opposite sides of the cell.

Explanation:

PLEASE HELP! WILL MARK BRANLIEST!

Fill in the correct answers in the boxes below.

Answers

1. Non renewable
2. Sedimentary rocks
3. Millions of years.

Answer:

9. nonrenewable resources

10. biomass

11. millions of years

hope this helps! Brainliest please?! :)

The relationships among different orders of millipedes are shown in the cladogram. Based on this cladogram, which statement best describes relationships among millipede orders? Stemmiulida is more closely related to Merocheta than Penicillata is to Merocheta. Spirostreptida is more closely related to Glomerida than Sphaerotheriida is to Glomerida. Polyzoniida is more closely related to Glomeridesmida than Sphaerotheriida is to Glomeridesmida. Merocheta is more closely related to Glomeridesmida than Glomerida is to Glomeridesmida.

Answers

Answer: Stemmiulida is more closely related to Merocheta than Penicillata is to Merocheta

Explanation:

Your question isn't complete as you didn't attach the picture needed to solve the question but I searched online and got the picture which is attached below.

Therefore, based on this cladogram, the statement best describes relationships among millipede orders is that Stemmiulida is more closely related to Merocheta than Penicillata is to Merocheta.

Therefore, the correct option is A

Do you think cell division stops after a new baby is born? Why or why not?
please help me i really need it lol

Answers

Answer: cell division does not stop after a baby is born bc if it were to stop then the baby would not grow

Which example below is a concern related to nuclear energy?

long-term storage of waste

supplemental energy may be needed if weather is not ideal for energy collection

can be unsightly and/or noisy

potential for floods

Answers

Answer:

C. can be unsightly and/or noisy

Explanation:

Answers A, B, and D correspond with fossil fuels (fracking, coal/gas mines), wind/environmentally-powered energy (turbines), and hydroelectric power (dams).

"Noisy" and "unsightly" are the most accurate descriptions of the nuclear energy process.

If this helped you, I'd appreciate Brainliest! <3 TY

Which of the following describes the role of nitrogen-fixing bacteria in the nitrogen cycle?
Nitrogen-fixing bacteria converts

A) nitrogen gas into ammonia
B) nitrates into nitrogen gas
C) ammonia into proteins
D) proteins into nitrates

Answers

Answer:

nitrogen gas into ammonia

A student lifted weights after
from school and felt his muscles
they began to burn. He couldn't continue
lifting weights after doing
exercise for a long time. Is
muscle fatigue is most likely
due to:
(1) the acceleration of the heartbeat and
exhaustion of the heart
(2) the accumulation of oxygen in the
lungs
(3) the lack of oxygen and the accumulation of
waste in muscles
(4) the lack of carbon dioxide in the
muscles

(1) the acceleration of the heartbeat and
exhaustion of the heart
(2) the accumulation of oxygen in the
lungs
(3) the lack of oxygen and the accumulation of
waste in muscles
(4) the lack of carbon dioxide in the
muscles

Answers

Answer:

lack of oxygen and accumulation of waste in the muscle

Amalia has the flu, a communicable disease that causes a cough and a runny nose. Which best describes how she likely got it?
She does not exercise.
She has a poor diet.
She touched the doorknob in a classroom.
She inherited it from her parents.

Answers

Answer:

is this multiple choice if not i have a better way of answering the third one like; as someone in her class has the flu the person touched the doorknob ,after a while she also touched it and without washing her hands  she touched her nose then the disease had  entered her body

YOU CAN SIMPLFY IT SINCE IF YOU TO BE IN A TEST YOU CANNOT REMEBER ALL THAT... :)

BUT I TRIED

Explanation:

Answer:

She touched the doorknob in a classroom.

Explanation:

anyone can get a cold By Touching something that was affected, or getting near someone who has been affected.

I hope this helped!

what is definition of biome

Answers

Answer:

a large naturally occurring community of flora and fauna occupying a major habitat, e.g. forest or tundra.

what are tissue made out of?

Answers

Answer:

Cells. If you are talking about tissue like Kleenex, then easy, soft fabric.

Explanation:

This is the correct answer(s) please trust meh.. And I hope I get Brainliest for my smart and amazing answer! Thank you and have a nice day! Bye!!!!

Answer:

paper

Explanation:

Genes code for
A. proteins

B. carbohydrates

C. lipids

Answers

Answer:

A. proteins

this is the answer of your question

hope it is helpful to you

What is it called when genetic information is exchanged between homologous chromosomes during prophase 1?

A. Meiosis

B. DNA Replication

C. Crossing Over

Answers

Answer:

C. Crossing Over

Explanation:

Crossing over, also called recombination, is the process by which non-sister chromatids of homologous chromosomes exchange a segment of their chromosomal material with one another. The process of crossing over occurs only in the prophase I stage of meiosis.

The process is responsible for genetic variation in the gametes produced, thereby, leading to organisms that are genetically unique.

Answer:

C. Crossing Over

Explanation:

The crossing over is called when genetic information is exchanged between homologous chromosomes during prophase 1.

Can someone pls check this

Answers

Answer:

I believe your answer is correct

Which three of the following examples are human activities that release carbon dioxide into the atmosphere? (Choose the three correct answers)

A
Fossil fuel combustion

B
Decomposition of plants

C
Agricultural activity

D
Deforestation

E
Volcanic eruptions

F
Tree respiration

Answers

Answer:

try a and d eeeeeeeeeeeeee

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