Answer:
The correct answer is: d. REs activity is best preserved by freezing the RE and thawing it out for brief periods of time as needed.
Explanation:
- Restriction enzymes can be defined as endonucleases that can recognize specific nucleotide sequence in a DNA (Deoxyribonucleic acid) sequence and cause breakage of phosphodiester bond in the DNA at the target site. Hence, it has the capacity of cleaving a DNA sequence.
- These are made up of proteins which are required to be present in the accurately folded conformation in order to function.
- Any form of alteration in the three-dimensional structure of the protein induced due to physical, chemical, mechanical or physiological factors can cause denaturation of the protein which in turn can render the protein non-functional.
- Freezing of restriction enzymes (REs) directly without the use of glycerol will cause the movement of water molecules within the proteins as well layering of water molecules on the protein surface.
- At low temperature these water molecules change to ice crystals which can alter the conformation of the protein or can cause breakage of peptide bonds in the proteins by physical force.
- This can cause the protein to get denatured and hence non-functional.
- Hence, it is never advisable to preserve REs by freezing directly without glycerol.
- Glycerol forms a layer around the protein molecules and prevents the protein molecules from coming into direct contact with the water molecules and hence prevents protein denaturation.
Answer:
A. Overtillage can increase the rate of humus decomposition
Explanation:
We refer to humus as any material of an organic nature that undergoes soil degradation. Humus is very important for agriculture because it has high nutrient levels that it provides to all crops. This causes more crop productivity, increases the producer's profit and increases the number of food available to the population.
Humus is a difficult to decompose material, but under favorable conditions it can decompose quite easily. Due to the presence of large amount of burnt organic matter in the soil, it is sometimes difficult to increase the humus content, so the exhaustion of this organic matter is caused by over tillage, especially in regions of tropical and sub-tropical climate, poorly managed. farmer protection and unprotected effects of erosion.
Answer:
The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10 percent of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes as heat.
Explanation:
Crossing over is important because it creates genetic variability.
<h3>What is crossing over?</h3>
It is the exchange of chromosomal segments between non-homologous chromosomes in a tetrad.
Since chromosomal segments contain genes at different loci, the exchange will increase the genetic variability of the new chromosomes.
Thus, the daughter cells carrying the recombined chromosomes will be genetically variable from not just the parent cell, but fellow daughter cells.
More on crossing over can be found here: brainly.com/question/19671756
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