LIFE PROCESSES

MRS GREN 

Living things have certain life processes in common. There are seven things that they need to do to count as being alive. The phrase MRS GREN is a way to remember them: 

Movement

Respiration 

Sensitivity 

Growth 

Reproduction 

Excreation

Nutrition

All living organisms on Earth are divided in pieces called cells. They are small compartments that hold all of the biological equipment necessary to keep an organism alive and successful on Earth. 

Cell Metabolism

A cell's daily operations are accomplished through the biochemical reactions that take place within the cell. Reactions are turned on and off or sped up and slowed down according to the cell's immediate needs and overall functions. At any given time, the numerous pathways involved in building up and breaking down cellular components must be monitored and balanced in a coordinated fashion. To achieve this goal, cells organize reactions into various enzyme-powered pathways.

Factors affecting the rate of enzyme activity

The rate of enzyme activity increases with as temperature increases until the best temperature, then falls to zero as the enzyme is denatured. This means that the protein changes shape and the active site is no longer complementary to the substrate molecule.
How the cell gets its energy

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. Cellular nutrients come in many forms, including sugars and fats. 

Cellular respiration 

Cellular respiration is the process by which the chemical energy of "food" molecules is released and partially captured in the form of ATP. Carbohydrates, fats, and proteins can all be used as fuels in cellular respiration, but glucose is most commonly used as an example to examine the reactions and pathways involved.
Respiration is a series of reactions in which energy is released from glucose. Aerobic respiration is the form of respiration which uses oxygen. It can be summarized by this equation:
glucose + oxygen → carbon dioxide + water (+ energy) Energy is shown in brackets because it is not a substance. Notice that: Glucose and oxygen are used up Carbon dioxide and water are produced as waste products.

Aerobic respiration 

Aerobic respiration happens all the time in the cells of animals and plants. Most of the reactions involved happen inside mitochondria, tiny objects inside the cytoplasm of the cell. The reactions are controlled by enzymes.
Anaerobic respiration 

Not enough oxygen may reach the muscles during exercise. When this 

happens, they use anaerobic respiration to obtain energy.Anaerobic respiration involves the incomplete breakdown of glucose. It releases around 5% of the energy released by aerobic respiration, per molecule of glucose. The waste product is lactic acid rather than carbon dioxide and water:glucose → lactic acid (+ little energy) 

Oxygen debt 

Aerobic respiration provides enough energy to keep the over worked muscles going for a short period, but continuing the “burst” activity makes lactic acid build up in the blood stream, producing muscle cramps the person then has to rest to oxidise the lactic acid fully. This uses oxygen. The volume of oxygen needed to completely oxidise the lactic acid that builds up in the body during anaerobic respiration is called the oxygen debt.

Cells, tissues, organs and organ systems

Pls. remember that the below process doesn't only occur to the circulatory system but to other organ systems too.