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Likurg_2 [28]
3 years ago
10

The opening and closing of the heart valves is caused by

Biology
1 answer:
Rashid [163]3 years ago
3 0

Answer:

pressure changes of alternating contraction and relaxation during the cardiac cycle.

Explanation:

Opening and closing of heart valves are regulated by changes in the blood pressure of various heart chambers during the cardiac cycle. During atrial systole, the higher blood pressure in the atria opens both AV valves and forces the blood to enter the ventricles. The semilunar valves are closed. During ventricular systole, the higher blood pressure in the ventricles opens both semilunar valves to allow the blood to enter the pulmonary trunk and aorta. At this time, both  the atrioventricular valves are closed.

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NEED HELP QUICK PLEASE HELP
kozerog [31]

Answer:

Question 1

D

Question 2

C

Question 3

D

Explanation:

1. An ecosystem is MOST likely to return to its original condition after Tall prairie grass burns after being struck by lightning.

Here is a research paper in which they explained how this happened. (Komarek, E. V. (1971). Lightning and fire ecology in Africa. In Tall Timbers Fire Ecology Conference (Vol. 11, pp. 473-509).)

2. In some national parks, controlled fires are maintained by firefighters. The major reasons for using controlled burns to maintain certain ecosystems is to give nonnative plants a chance to colonize the region.

A recent article provided the insight of this situation (Xanthopoulos, G., Delogu, G. M., Leone, V., Correia, F. J., & Magalhães, C. G. (2020). Firefighting approaches and extreme wildfires. In Extreme Wildfire Events and Disasters (pp. 117-132). Elsevier.)

3. One reason for the change in the Galápagos ecosystem has been the introduction of species that were not on the island before, such as donkeys, goats, cats, dogs, and insects. The introduction of nonnative species MOST likely disrupt the balance of life on the islands due to greater competition for limited food sources.

Scientist said that food competition is actually a struggle to survive in any ecosystem here is the reference paper (Eckhardt, R. C. (1972). Introduced plants and animals in the Galapagos Islands. Bioscience, 22(10), 585-590.)

5 0
3 years ago
4) Cellular respiration allows organisms to release the energy stored in the chemical bonds of glucose, C6H12O6. The energy in g
Colt1911 [192]
A) Water as it is a wats product
8 0
3 years ago
Which is the source in variations in a population of organisms?
Mashutka [201]

Answer:

The change in environment

Explanation:

Because they need to adapt to live

3 0
2 years ago
Read 2 more answers
A doença vitiligo afeta qual doença do corpo?
Zolol [24]

Olá! Eu acredito que você colocou sua pergunta na categoria errada. Não se esqueça de fazer a pergunta na seção de idiomas estrangeiros para evitar que a pergunta seja excluída.

Com sua pergunta real, não acho que posso ajudá-lo com isso, e sinto muito por isso.



4 0
3 years ago
Under ideal conditions, how do allele frequencies change over time?
dedylja [7]
D- the frequency of the recessive alle increases over time
3 0
3 years ago
Read 2 more answers
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