With a light microscope one can view the nucleus and endoplasmic reticulum, large vacuoles etc
The resolution of a light microscope is dependent on the wavelength of light that is the main beam of illumination. Light has approximately 0.4 um (UV)- 0.7um (Infrared) wavelength. Organelles smaller than about 0.5 um will be difficult to discern with a light microscope.
With an electron microscope one can view, in addition, even the ribosomes and mitochondria, chromosomes, tubules etc.
An electron microscope can discern very minute details of a cell. This is because its resolution is dependent on the very small wavelength of a beam of electrons which is approximately 0.002 um (about 10,000 times powerful than a light microscope)
Soil erosion is defined as the wearing away of topsoil. Topsoil is the top layer of soil and is the most fertile because it contains the most organic, nutrient-rich materials. Therefore, this is the layer that farmers want to protect for growing their crops and ranchers want to protect for growing grasses for their cattle to graze on.
Answer:
1. sympathetic
2. parasympathetic
Explanation:
The sympathetic division of the autonomic nervous system triggers the release of stress hormones from adrenal medulla under emergency conditions. There is a series of physiological responses such as increased heart and breathing rate, an increased flow of blood to skeletal muscles, dilation of pupils, etc. These events helped Nasim to fight the stress conditions.
Once she was relieved, the parasympathetic system is activated that shut down the physiological responses generated by sympathetic division. It slows down the breathing and heart rate and triggers the digestion and absorption of nutrients to restore the energy level of cells.
Answer:
E. It takes a picture of the brain according to oxygen levels. More oxygen in an area indicates more activity in that area.
Explanation:
Haemoglobin is diamagnetic when oxygenated but paramagnetic when deoxygenated. This distinction in magnetic characteristics leads to tiny variations in the blood MR signal. Since blood oxygenation differs, these variations can be used to identify brain activity depending on the concentrations of neural activity.
