The correct answer is option (A) Variation in the strawberry plants.
When the effect of fertilizer on the growth of two strawberry plants is tested, unavoidable source of experimental error is the variation in the strawberry plants. Variation refers to the deviation or differences from the normal plant which can be due to genetic variation. It is due to change in the DNA sequence. If any one of the two plants being tested show variation, the rate of metabolism differs and changes the growth pattern of the plant. The rate of absorption of water and nutrients is effected which brings change in the growth of the plant and causes an error in the experiment and the result.
A particular single-celled organism uses radiant energy to fix carbon as sugars. This organism generates ATP by breaking down sugars through a process that uses oxygen. This organism is aerobic autotroph.
Autotrophs produce their own food from the substances available in their surroundings using light through photosynthesis or chemo-synthesis.
<span>They are proteins that are secreted from fat cells to help regulate energy balance.</span>
Fruit flies produce offspring relatively fast and have specific traits, such as eye color and body color/shape. They are easy to observe and their traits are easily traced throughout the next generations.