The two sides of a nerve cell membrane have unequally distributed ions ( Na+ and K+). Sodium is inside, while potassium is outside. Carriers actively transport them. This active transport mechanism is called Sodium-Potassium Pump. Without stimulus, sodium channels are closed while some of the potassium channels are open.
Stimulus (depolarization) will cause the sodium channels to briefly open and the positively-charged ion diffuses into the nerve cell. The membrane potential becomes positive. The potassium channels open and positively-charged potassium diffuse out. With respect to the outside, the inside will become less positive again.
A subsurface rock layer that is composed of clay and bedrock and is an impermeable barrier to water flow would be described as a(n) <u>aquifer(option b)</u>.
An aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials (gravel, sand, or silt).
The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Aquifers occur from near-surface to deeper than 9,000 metres (30,000 ft).
There are three different types of aquifers: confined, unconfined, and perched. Recharge zones are typically at higher altitudes but can occur wherever water enters an aquifer, such as from rain, snowmelt, river and reservoir leakage, or from irrigation.
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The arrangement of homeotic genes along chromosomes of vertebrate and invertebrate animals corresponds to the expression pattern of the genes along the anterior-posterior axis of the developing embryo.
<h3>What are homeotic genes?</h3>
- Homeotic genes are a group of body pattern forming genes which control the development along the anterior- posterior axis of the developing embryo.
- These encode transcription factors which control and specify the genes involved in body patterning. These provide identity to the segments during embryo formation.
- Genes located in the 5’ end act on posterior side whereas the genes on 3’ end act on anterior region.
- Homeotic genes are evolutionary conserved and control body specification, patterning and differentiation.
- The loss of function of any of the gene changes the body pattern and affects the development.
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Cellular respiration is the process by which cells in plants and animals break down sugar and turn it into energy, which is then used to perform work at the cellular level. The purpose of cellular respiration is simple; it provides cells with the energy they need to function.
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A person shall consume at least 750
mg of sodium ion daily to remain in electrolyte balance if he/she loses 750 mg/day
of sodium in urine, sweat and feces. Electrolyte is a substance that
can carry electrical current across cell membranes.
