Explanation:
In the majority of cases, the extra copy of chromosome 21 comes from the mother in the egg.
In a small percentage (less than 5%) of cases, the extra copy of chromosome 21 comes from the father through the sperm.
In the remaining cases, the error occurs after fertilization, as the embryo grows.
Is there any multiple choice answers <span />
Answer:
Google is great sometimes
Explanation:
Type your question in google
Fish are cold-blooded or poikilothermic, meaning that their body temperatures vary with the surrounding temperature. During the cold of winter fish become less active. They find little pockets out of the way of fast moving water where they can stay still and conserve energy.
Answer:
The correct answer will be option-D
Explanation:
Arid areas are the regions of the world which can be marked with the lack of water conditions, high light intensity and very low rainfall.
Water is one of the primary requirement of the plant without which no plant can survive but the adaptability to the environment allows the existence of the life on earth.
There are known species of plants which are adaptive to such arid conditions.
If a farmer is interested in growing plants in such arid conditions hen he should select the plants which could better be adapted to survive in the arid conditions either by avoiding arid condition like storing water, low transpiration, extensive root system and many others.
Thus, Option-D is the correct answer.
