Answer:
I and III only
Explanation:
Crop rotation is a farm practice that involves cultivating different species of crops on the same land at different seasons. In other words, the different crops are rotated. Crop rotation is done for various reasons including; improvement of soil fertility, pest and disease control etc.
In this case, a crop rotation of various grains and legumes would be an appropriate solution for the following problems:
- The nutrients in the soil on a farm are being depleted: Legumes are known to be rich in nitrogen and hence add nitrogen to the soil due to the nitrogen-fixing microbes in their roots. Hence, rotating between grains and legumes can help return the depleted nutrients (by grains) to the soil.
- A particular kind of pest is infesting the soil on a farm: Most pests are usually crop-specific, hence, planting only one type of crop can make that soil be infested with a particular kind of pest. However, rotating between crops such as grains and legumes can make a particular pests become scarce or less populated.
<u>Answer:</u>
The invention of agriculture, advances in medical technology that have greatly reduced the human death rate and he rapid increase in the uses of fossil fuels, fertilizers, metal ores, and other resources.
Option: (A), (C) and (D)
<u>Explanation:</u>
- The Great Acceleration refers to the humanity’s impact upon the Earth’s geology and its ecosystems caused by continual and surge in growth of human activity.
- It was first recorded in mid-20th century and is continuing to this day. The 'invention of agriculture', advancement in medical technology which reduced the death rate, rapid increase in use of 'fossil fuels', 'fertilizers' and other resources contributed to global changes.
- Agriculture allowed us to produce more food and population increased rapidly.
- Fossil fuels created a surge in production of Green House Gases and global temperature began to rise.
The normal membrane potential inside the axon of nerve cells is –70mV, and since this potential can change in nerve cells it is called the resting potential. When a stimulus is applied a brief reversal of the membrane potential, lasting about a millisecond, occurs. This brief reversal is called the action potential
<span>A stimulus can cause the membrane potential to change a little. The voltage-gated ion channels can detect this change, and when the potential reaches –30mV the sodium channels open for 0.5ms. The causes sodium ions to rush in, making the inside of the cell more positive. This phase is referred to as a depolarisation since the normal voltage polarity (negative inside) is reversed (becomes positive inside). </span>
<span>Repolarisation. At a certain point, the depolarisation of the membrane causes the sodium channels to close. As a result the potassium channels open for 0.5ms, causing potassium ions to rush out, making the inside more negative again. Since this restores the original polarity, it is called repolarisation. As the polarity becomes restored, there is a slight ‘overshoot’ in the movement of potassium ions (called hyperpolarisation). The resting membrane potential is restored by the Na+K+ATPase pump.</span>
The answer is apex and base. To simplify, the apex of the heart rests on the diaphragm and from its base, the great vessels emerge. In addition, blood vessels that are nearer to the pumping heart and must enlarge to endure pressure variations are named elastic arteries and foramen ovale permits blood to pass from the right to the left atrium, therefore avoiding to pass the fetal lungs.