Answer:
Given:
Number of colonies on plate = 40
Amount of DNA used for transformation = 100ng
Volume of competent cells used = 100ul
Total volume = 1ml (1000ul)
Volume plated for growth = 200ul
The amount of cells transformed per 1 µg of DNA is called the transformation efficiency
(CFU is colony forming units) => (number of colonies on plate/ng of DNA plated) X 1000 ng/µg = CFU/µg of DNA
Amount of DNA used for plating = 100ng * (200/1000)
= 100ng * (1/5)
= 100/5 = 20ng
Efficiency calculation = 40 colonies / 20ng = 2 colonies/ng
(2 colonies/ng) * (1000 ng/µg) = 2000 CFU/ug DNA
Transformation efficiency = 2000 Transformants / ug DNA
= 2 x 10³ Transformants / ug DNA
Explanation:
Efficiency of transformation is highest in the 100 pg-1 ng range, so Low transformation efficiency could be because of high amount of DNA used for transformation.
The correct answer is letter (<span>C) The polar air mass moves south to replace the rising maritime tropical air mass.</span> These air masses are bringing cold air to warmer areas most especially during the winter and cool. These air masses are stable and usually does not form much cloud. While the Continental Polar air move down south, across the warmer land, the lower part of the air mass is modified and thus few clouds are formed.
Nitrogen is the major nutrient required by grass and is used to
stimulate high growth rates and is key to achieving high yields, however
if too much nitrogen is applied this can have a negative effects on
quality.
High rates of nitrogen can also cause problems with silage
fermentation due to excess nitrate having a negative impact on the
fermentation process and will produce silage that is less palatable and
the animals will be less keen to eat it.
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Nitrate is generally taken up by grasses quicker than it is
incorporated into proteins and until used this excess known as luxury
uptake is stored in the leaves. Excess nitrate will be present if
insufficient time is allowed between application and mowing and can also
occur under conditions of poor growth eg low light levels, cool
temperatures. It is also a problem if there is a dry spell after
application, when nitrate cannot be taken up by the roots, followed by a
period of wet weather that results in luxury uptake. The plant cannot
convert it to protein quickly enough so it accumulates in the plant.
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High rates of nitrogen may cause a reduction in crop sugars as they
are used to provide energy for the increased rate of plant growth and
for the manufacture of plant proteins and this increased growth rate may
in turn lead to lower crop dry matter content although in practice this
is often not significant.
Excess nitrate can be avoided by following the Grassland Rule to apply nitrogen at the rate of no more than 2.5 kg N/ha/day.
secondary succesion takes place
Answer:
1. Ends of the respiratory branches are called alveoli.
2. C. To control blood flow to different areas of the body depending on activities
Explanation:
1. The trachea divides into left and right primary bronchi which in turn divide multiple times upon entering the lungs and make the bronchial tree.
The final branches of the bronchial tree are the terminal bronchioles that lead to alveoli. The alveoli are the balloon-shaped structures and serve as the site of gas exchange between the blood and inhaled air.
2. The opening and closing of sphincters of capillary beds regulate the direction of blood flow. The opening of sphincters allows the blood to flow into associated branches of capillary beds while closed sphincters direct the blood from arterioles to venules via thoroughfare channel.
This local change in blood flow is responsible for the autoregulation of blood flow to different tissues to match their respective metabolic demands. For example, during physical activity, more blood is directed to skeletal and cardiac muscles.
