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Lady bird [3.3K]
2 years ago
11

Why does menstruation happen?

Biology
2 answers:
DedPeter [7]2 years ago
6 0
The menstrual<span> cycle </span>occurs<span> due to the rise and fall of hormones</span>
Troyanec [42]2 years ago
4 0

During that, menstruation stops because the blood came from the uterus protect it and give nourish to the fertilized egg. It usually happen because a sperm cell meet it. When menstruation happens, it develop an egg cell and carried out with the lining of the uterus called the endumetrium because it dies.

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Look at the diagram which system does it show​
Maksim231197 [3]

Answer:

This is the digestive system.

Explanation:

We can tell that this is the digestive system because we can see #1: The stomach, #2: The small intestine, #3: The large intestine, and #4: The liver. Hope this helped!

4 0
2 years ago
Which aquifer listed below would be the most effective in purifying polluted groundwater, and why?
11Alexandr11 [23.1K]
The aquifer which will be most effective in purifying polluted ground water is AN AQUIFER COMPOSED MAINLY OF SAND.
An aquifer refers to a zone of permeable rock strata which transmit ground water freely. An aquifer must be permeable and porous. Ground water can be extracted from an aquifer by using a water well.
7 0
2 years ago
Under a microscope, gram-positive bacteria (when dyed with the gram stain) appear _____.
DedPeter [7]

Under a microscope, gram-positive bacteria (when dyed with the gram stain) appear in purple-colored structures due to the peptidoglycan cell wall.

<h3>What are gram-positive bacteria?</h3>

Gram-positive bacteria are microorganisms (bacteria) that may be colored with crystal violet stain due to the presence of a peptidoglycan-based cell wall.

In conclusion, under a microscope, gram-positive bacteria (when dyed with the gram stain) appear purple-colored structures due to the peptidoglycan cell wall.

Learn more about gram-positive bacteria here:

brainly.com/question/14543191

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7 0
1 year ago
The first organisms that perform photosynthesis involves about two.2 billion years ago. During the next few million years their
balandron [24]

Answer:

<em>The correct option is A) an increase in oxygen levels, which led to the extinction of many anaerobic organisms.</em>

Explanation:

Photosynthesis can be described as a process in which food (glucose) is produced by photosynthetic organisms by using carbon dioxide, water along with light energy from the sun. Oxygen is released as a by-product of this reaction. The process of photosynthesis initially allowed for oxygen gas to get accumulated in the air. This caused the rise of aerobic organisms who required oxygen for respiration. Before the photosynthesis organisms evolved, there was not enough oxygen gas on earth to support the life of aerobic organisms.

6 0
2 years ago
What is the function of platelets ?<br>​
sergij07 [2.7K]

Explanation:

Form temporary platelet plugs to stop bleeding.

Dissolve blood clots when they are no longer needed.

5 0
2 years ago
Read 2 more answers
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