Answer:
Cleavage is a process in which cell is divided into several parts without increasing in size. There are 4 stages of cleavage i. e. 2-cell, 4-cell, 8-cell and 16 cell stages. 2 cell embryo cleavage occurs after 30 hours of fertilization. 4 cell embryo cleavage occurs after 48 hours. 6 cell embryo cleavage occurs on third day of fertilization. 8 cell embryo cleavage occurs on fourth day of fertilization and more than 100 cells are formed.
Animals with bilateral symmetry can be divided equally along only one plane.
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Answer:
Xylem cells have no cytoplasm or end walls, meaning they form a tube through which water can pass freely to allow water transport. Lignin strengthens the cell walls, helping to support the plant.
Answer:
A. Many environments are not suitable for fossil formation.
New Moon. This is because the light from the sun is being pointed at the other side of the moon ( the side we can not see ).
