Hello there Jonnromeroo, thank you for asking a question here on Brainly!
You Asked ➤ Which of the following processes begins when a star enters the main sequence?
↴ OUR CHOICES ↴
A: Nuclear fission
B: Nuclear fusion
C: Condensation of a nebula
D: Appearance of a supernova
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Answer ➤ B: Nuclear fusion
Explanation: When a star begins the process of being created, it is hot and dense. Really hot and dense! It begins to start fusing with helium which is the start of its main sequence called nuclear fusion.
I hope this answer is helpful to you, but please let me know if you have any other questions regarding it.
<em>- Qamar </em>
Cell is a simple unit of life surrounded by a membrane that contains macromolecules and molecules associated with each other.
<h3>What is cell?</h3>
The smallest unit that makes up all living organisms and the tissues of the body. A cell consists of three main parts i.e. the cell membrane, the nucleus, and the cytoplasm. The cell membrane surrounds the cell and its function controls the substances that go inside of cell and out of the cell. A nucleus is the membrane that enclosed organelle within a cell which contains the genetic material. The cytoplasm is the gel-like fluid inside the cell that provides a medium for chemical reaction.
So we can conclude that Cell is a simple unit of life surrounded by a membrane that contains macromolecules and molecules associated with each other.
Learn more about macromolecules here: brainly.com/question/5246898
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While mitosis produces 2 daughter cells from each parent cell, meiosis results in 4 sex cells, or gametes in males and 1 in females. Unlike the cells created by mitosis, gametes are not identical to the parent cells. In males, meiosis is referred to as spermatogenesis because sperm cells are produced.
Yes, Jan should undergo genetic sequencing.BRCA1/BRCA2 are the causes of 20-25% of all hereditary breast cancers, so if Jan's mother and sister both have breast cancer, then the odds are that she has BRCA1 as well.
