According to the theory proposed by Harry Hess, what causes continents to move?
The correct answer is : seafloor spreading.
Earlier, in 1912 Alfred Wegener produced evidence that the continents are in motion but this idea was shelved as he could not explain what forces the continents to move. So, almost 50 years later Harry Hess confirmed Wegener's ideas by using the evidence of seafloor spreading to explain what moved continents.
Natural selection is a specific mechanism of evolution in which the heritable traits help an organism to survive and reproduce successfully. answer B
Answer:
Soil condition directly affects crop growth.
Explanation:
Soil condition affects the crop growth directly. If a soil is in fertile condition then the growth of crop which is growing in such soil will be good but if the soil is infertile then the crop will not grow to its fullest. A fertile soil is the one which has optimum condition for growth of a crop like suitable pH, moisture retention capacity, good amount of nutrients & minerals like nitrogen, phosphorus, sodium, potassium, magnesium etc. If a soil is rich in all these constituents then the crop which is growing in this soil will be healthy. But, if a soil is infertile then the crop which is growing on that soil will be under stress and will not be able to grow completely.
Explanation: Elephants have been extensively hunted for ivory for more than 300 years, natural selection is often proposed as the underlying mechanism for an increase in the proportion of tuskless or small-tusked elephants in a population.
