Answer:
Explanation:
Four conditions are needed for natural selection to occur: reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population.
ORR
Struggle for existence, variation and inheritance. These are said to be the necessary and sufficient conditions for natural selection to occur.
A) .was immediately accepted
Explanation:
The theory of plate tectonics was immediately recognized as the explanation for the moving continents. It provided a more scientific background as why continents drift apart and the seafloor keeps spreading.
- The theory explains that the earth is broken up into series of slabs called lithosphere which moves on the weak, ductile and fluid asthenosphere.
- The movement of part of the earth mantle provided the mechanism through which the lithosphere moves. This is now known as the mantle convection.
- This theory provided a scientific mechanism through which the plate moves and seafloor spreads.
- It was immediately accepted when the theory was propounded by Alfred Holmes in the 1930s
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Answer:
The correct answer is option C.
Explanation:
Before meiosis, DNA that is stacked into chromosomes must replicate. Before replication, the sex cell has two copies of each chromosome, one from mother, and one from father.
DNA replication takes place in the same manner as it does during mitosis. After the chromosome replication, the homologs are double in number, and each chromosome now has a homologous pair of chromosomes.
Thus, the correct answer is option C.
Answer:
Myelination
Explanation:
Myelin is a fatty substance composed of lipids which surrounds the axons of the nerve cells in the central nervous system. The myelin is formed by the oligodendrocytes in CNS and Schwann cells in PNS.
The plasma membrane of the oligodendrocytes containing the myelin covers the axons of the neurons in spiral fashion thus proving a sheath around through the process called "myelination".
This myelin sheath protects the neurons from the external environment as well as insulates the neuron which increases the efficiency of the impulse.
Thus, Myelination is the correct answer.
