ANSWER:
Lesions are areas of damage to motor neurons. Damage to upper motor neurons stops the signals your muscles need to move. When your muscles don't move for a long time, they become weak and stiff. Over time, it can become harder to walk and control your movement.
Explanation:
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Crossing over contributes to genetic variation by exchanging chromosomal segments between non-sister chromatids of homologous chromosomes.
What is crossing over?
- Crossing over is the exchange and recombination of genetic components between the homologous chromosomes.
- This occurs in the pachytene stage of the meiosis-1 of the meiotic division.
- Crossing over occurs with the help of an enzyme and the enzyme responsible for crossing over is called Recombinase.
Thus, crossing over contributes to genetic variation by exchanging chromosomal segments between non-sister chromatids of the homologous chromosomes.
Learn more about crossing over: brainly.com/question/927405
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A lysosome is a membrane-bound cell organelle that contains digestive enzymes. Lysosomes are involved with various cell processes. They break down excess or worn-out cell parts. They may be used to destroy invading viruses and bacteria, A vacuole is a membrane-bound cell organelle. In animal cells, vacuoles are generally small and help sequester waste products. In plant cells, vacuoles help maintain water balance.
