Answer: Women are carriers for the disease hemophilia because hemophilia is an X-linked disease. The recessive allele for the disease is found on the X chromosome.
The sons of carrier women get hemophilia because males have one X chromosome and one Y chromosome. The sons of a carrier woman may inherit the affected X chromosome from their mother, and a Y chromosome from their father. They have only one X chromosome and one it's affected, will result in hemophilia.
Explanation: Women are carriers because in most cases, only one of their two X chromosomes are affected. The two female X chromosome is rarely affected.
Daughters of carrier women will not get the disease because they need two affected X chromosomes to manifest the disease. So even if they inherit one affected X chromosome from their mother, the second X chromosome they will inherit from their father will be normal. Therefore, daughters of carrier women can only be carriers.
Answer:
contractile vacuole
Explanation:
contractile vacuole is used for balance of water,salt etc
The medulla has the ascending and the descending tract which function to link the brain with the spinal cord.
<h3>What is the role of medulla?</h3>
- Medulla oblongata is the lowermost part of the brain.
- It is located at the place where the brain and the spinal cord connect thus it carries nerve signals between the brain to spinal cord thus help the entire body to communicate.
- It controls biological processes like blood pressure, breathing and heartbeat.
- Ascending tract functions to carry sensory information from the body (e.g.: pain) from the spinal cord to the brain (upwards).
- Descending tract carry motor information (e.g.: instructions to move the arm) from the brain down the spinal cord to the body (downward).
- Damage to medulla can lead to respiratory failure, paralysis, or loss of sensation.
Learn more about medulla here:
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In multicellular plants and animals, however, meiosis is restricted to the germ cells, where it is key to sexual reproduction. Whereas somatic cells undergo mitosis to proliferate, the germ cells undergo meiosis to produce haploid gametes (the sperm and the egg).
The first, second, and fourth statements are correct.
