Cells, like humans, cannot generate energy without locating a source in their environment. However, whereas humans search for substances like fossil fuels to power their homes and businesses, cells seek their energy in the form of food molecules or sunlight. In fact, the Sun is the ultimate source of energy for almost all cells, because photosynthetic prokaryotes, algae, and plant cells harness solar energy and use it to make the complex organic food molecules that other cells rely on for the energy required to sustain growth, metabolism, and reproduction (Figure 1).
Cellular nutrients come in many forms, including sugars and fats. In order to provide a cell with energy, these molecules have to pass across the cell membrane, which functions as a barrier — but not an impassable one. Like the exterior walls of a house, the plasma membrane is semi-permeable. In much the same way that doors and windows allow necessities to enter the house, various proteins that span the cell membrane permit specific molecules into the cell, although they may require some energy input to accomplish this task (Figure 2).
Answer:
28%
Explanation:
Primero <u>calculamos los mililitros de etanol presentes en la primera solución</u>:
- 200 mL * 70/100 = 140 mL etanol
Para calcular el nuevo porcentaje en volumen, dividimos los mililitros de etanol (<em>que permanecen iguales durante el proceso de dilución</em>) entre el volumen final.
- Volumen final = 200 mL + 300 mL = 500 mL
- % Volumen de Etanol = 140 mL / 500 mL * 100% = 28%
Unshared/lone pairs of valence electrons :)
Answer:
The volume of nitrogen oxide formed is 35.6L
Explanation:
The reaction of nitric acid with copper is:
Cu(s) + 4HNO₃ → Cu(NO₃)₂ + 2NO₂(g) + 2H₂O(l)
Moles of copper are:
Moles of nitric acid are:
As 1 mol of Cu reacts with 4 moles of HNO₃:
0.697 mol Cu × (4mol HNO₃ / 1mol Cu) = 2.79 moles of HNO₃ will react. That means Cu is limiting reactant.
Moles of NO₂ produced are:
0.697 mol Cu × (2mol NO₂ / 1mol Cu) = <em>1.394 moles of NO₂</em>
Using PV = nRT
<em>Where P is pressure (735torr / 760 = 0.967atm); n are moles (1.394mol); R is gas constant (0.082atmL/molK); T is temperature (28.2°C + 273.15 = 301.35K). </em>
Thus, volume is:
V = nRT / P
V = 1.394mol×0.082atmL/molK×301.35K / 0.967atm
V = 35.6L
<em>The volume of nitrogen oxide formed is 35.6L</em>
Conduction
Explanation:
Stirring a pot with a metal spoon thereby making the spoon hot in the hand is a mode of heat transfer called conduction.
Heat is form of energy that causes differences in temperature between two bodies.
- There are three modes of heat transfer which are conduction, convection and radiation.
- Radiation is a form of heat transfer that does not involve a material medium.
- Convection is heat transfer in fluids that involves movement of the materials of the medium.
- Conduction is a mode of heat transfer in solids that involves movement of the materials of the medium.
learn more:
Heat transfer from sun brainly.com/question/1140127
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