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In the human digestive system, food enters the mouth and mechanical digestion of the food starts by the action of mastication (chewing), a form of mechanical digestion, and the wetting contact of saliva.
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Answer:
There are four principles at work in evolution—variation, inheritance, selection and time. These are considered the components of the evolutionary mechanism of natural selection.
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Answer:
50%
Explanation:
Let's assume that the X linked allele "a" gives the disorder. Therefore, the genotype of the affected man would be X^aY while the genotype of the carrier woman would be X^aX. A cross between X^aY man and X^aX woman would produce progeny in following phenotype ratio: 1 affected daughter: 1 affected son: 1 normal but carrier daughter: 1 normal son.
Therefore, there are 50% chances that their children can express the disorder.
Correct answer: B). Food and fossil fuels
The energy can not be created nor destroyed but it can be transformed into another form. The ultimate source of energy on this planet is the sun, the sun provides sunlight where sunlight is converted into chemical energy, which is used by plants to prepare food. Then we consume food prepared by plants to get energy and perform various types of work like movement, reproduction, growth etc. In this, the chemical energy is converted into mechanical energy.