AC 1.1
By
Life Processes common to living organisms
Laura Judges

TABLE OF CONTENTS
Chapter 1 page
Introduction to life processes 2
Chapter 2 page
Movement 2-3
Chapter 3 page
Repoduction 3
Chapter 4 page
Sensitivity 3-4
Chapter 5 page
Growth 4
Chapter 6 page
Respiration 5
Chapter 7 page
Excretion 5-6
Chapter 8 page
Nutrition 6-7
Chapter 9 page
Conclusion 7-8
Chapter 10 page
Bibilography 9 Introduction to life processes
The most basic of living things consist of just one single cell for example bacteria, while more complex organisms such as humans are multi-cellular. An organism is defined as an individual animal, plant or single-celled life form. Therefore the cell is considered the smallest unit of life competent of a self-sufficient existence. There are seven things that all living organisms from bacteria to plants to animals all have in common and whether something is living or not is usually compared to the seven life processes. These processes are movement, reproduction, sensitivity, growth, respiration, excretion and nutrition. The acronym ‘MRS GREN’ will be used when discussing the processes of life movement All living things move to some kind of degree and this is the most apparent within the animal kingdom. Animals are able to physically move themselves from one place to another; humans will usually use their muscles in order to be able to move where as other animals may have to hop, crawl, swim or fly. Movement is very important for gathering sustenance and escaping predators. Movement within plants is generally by growth, many of the higher part of plants for example flowers, branches and roots will move as they grow however this process can be quite slow. Many plants follow the movement of the sun through the sky during the day and will often turn their flowers or leaves to face the direction of the sun for example the sunflower. Some plants are able to move certain parts quite fast for example the Venus fly trap which will swiftly close its leaves in order to begin to digest its pray.

Movement can also be an internal process for example the movement of the heart muscle which pumps blood around the body or even the muscles that thrust food all the way through the digestive system. Internal processes of movement can also include the circulatory system, insects have an open circulatory system fish have a single circulatory system and mammals have a double circulatory system. The purpose of a circulatory system is to assist in the transport of fluid around the whole body for example blood. An open circulatory system is where the blood is not enclosed in vessels but is able to circulate within body spaces. Single circulatory systems allow the blood to flow through the heart once during a complete circuit of the body. A double circulatory system allows blood to flow through two circuits – the pulmonary and the systematic circuits. Pulmonary circulation is the movement through the lungs and back to the heart. Systematic circulation is the movement of blood around the body and back to the heart.

repoduction

Without reproduction living things would not endure more than one generation. There are two types of reproduction: sexual and asexual. Sexual reproduction is where two parent organisms, one male and one female are needed in order to reproduce, for example humans. Asexual reproduction is where only one parent organism is present in order to reproduce further this can include bacteria and some plants. Animals, humans and plants all reproduce however in slightly different ways. Humans give birth to babies whereas some animals may lay an egg which contains their young and will then hatch for example chickens, butterflies and frogs. The offspring may not; to begin with, look like the parents however will eventually develop to do so.

Plants are also able to reproduce, however it is not in the same was as humans and animals. Most plants have the ability to make seeds in order to reproduce; some attach themselves to animals and humans which will then be transported to another location where it can then reproduce, other seeds are very light and have the ability to move in the wind in order to find another location.

The majority of trees and shrubs that have fruit grow seeds within them so that when a bird, human or animal consumes the fruit and seeds are unable to be digested so will be excreted some time later, when these seeds settle and they have enough space, water and nutrients they will then begin to germinate and continue the life process of the plant.. Plants also have the ability to produce exact copies of the original product. The most important function of reproduction is to uphold the population of a specific species without it becoming extinct. sensitivity Sensitivity is an important function of an organism to help it survive in their immediate surroundings and respond to stimulants that could have an effect on them. All living organisms have an awareness of changes in their environment. Plants appear to be less sensitive to their environment and their responses are slower than that of animals. They are responsive to gravity which is why the roots grow down into the soil where they will be able to get water and nutrients from. They are also sensitive to light, which is why often plant leaves face towards the light source. Some plants such as runner beans, sweet peas have the ability to respond to the contact of a support pole. Some plants do have the ability to move certain parts quite fast for example the Venus fly trap which will swiftly close its leaves in order to begin to digest its pray.

In animals, the body cells that are able to detect stimulants are called receptors which are often contained within a sense organ, for example the eye is a sense organ within which the retina contains rod and cone cells which are receptors. These sense organs are eyes for sight, ears for hearing, nose for smell, tongue for taste and skin for touch. All five senses are ideal to help avoid predators or to capture pray which would provide the nutrients and nourishment that is vital for survival. Rapid communication and response to stimulants, such as light, sound and scent are essential to an animal’s well-being and survival.
Growth

All living things need to grow in order to enable undeveloped organisms to cultivate new cells which can help them develop and reach their fully grown size. Plants continuously grow right the way through their existence. There are three major functions that are important to plants growth and development; these are photosynthesis, respiration and transpiration. Photosynthesis can be described as the process of capturing light energy and then converting it into sugar energy within the presence of chlorophyll by means of carbon dioxide and water. Respiration is the process of burning sugars to gain energy for growth reproduction and other life processes. Finally, transpiration is the loss of water vapour through the stomata of leaves.

Animals and humans are much like plants with regards to continuously growing, however unlike plants, humans and adults will cease to continue growing in height when they reach adulthood. Mature organisms such as hair/fur and fingernails do continue to grow as long as they are gaining all the right nutrients that they can feed from.

With regards to cell growth this takes place during a process called mitosis. This is when new cells form and the nucleus makes a copy of itself which then divides into two to form two new cells. The cells that are formed could be used for growth, to provide new cells or to replace old and damaged ones which could then potentially hinder further growth development.

Bacteria has the ability to grow bigger by using nutrients that it has gained through the digestion of food products and energy released through respiration, when bacteria cells reach their optimum size they then split into two and the process will then continue to be repeated.

respiration

Respiration is a way of releasing energy from nutrients and foods such as sugar. It takes place in the mitochondria which are the structures that are found in the cytoplasm of cells. There are two types of respiration that can take place, aerobic respiration and anaerobic respiration. Aerobic respiration needs oxygen, humans and other animals are very dependent on this. They absorb the oxygen from the air and then expel carbon dioxide which has been produced.

Plants also respire aerobically, usually when photosynthesising as this is when they produce more than enough oxygen than what is needed for respiration to occur. Anaerobic respiration releases less energy than aerobic respiration. Organisms that are able to respire both aerobically and anaerobically will tend to respire aerobically as much as possible so that enough energy is received. Humans are able to respire both aerobically an anaerobically, this is evident when exercising as the oxygen supply can be insufficient to supply the amount of energy through only aerobic respiration so anaerobic respiration would also begin to take place.

There are many organisms that will only respire anaerobically, for example yeast which is a type of fungus. The yeast gathers energy from glucose without the presence of oxygen in order to produce carbon dioxide and ethanol. This process is called fermentation which helps to produce wine and other alcoholic substances. Breathing is the way in which organisms take in air for respiration, this process is generally limited to animals that have lungs for example birds, humans and reptiles. The role of the lungs is to extract the oxygen from within the air and then to expel carbon dioxide back into the air.

Other organisms have other ways of extracting oxygen and expelling carbon dioxide. These organisms can include fish that use their gills to complete the process. Plants and bacteria are unable to physically breathe in the sense that they do not have lungs; however they do absorb carbon dioxide and expel oxygen.

excretion

Excretion is the removal of chemical waste and other non useful substances that are produced from within cells. All organisms produce waste products that they need to eradicate. The build up of some waste matter can be harmful to the cell and organism that it is a part of, for example elimination of carbon dioxide made by respiration, a build up of carbon dioxide would increase the acidity within the cell and then cause the chemistry of the cell would become greatly affected along with the structure of the proteins.

Another example of excretion is humans and other mammals both produce a substance called urea. This is produced within the liver when compounds containing nitrogen such as amino acids are made when protein is digested. If the urea was allowed to build up it would slowly begin to poison the host, so in order to prevent this, the urea is removed via the kidneys and passed out of the body as urine along with water and other waste chemicals.

Plants are less complex in structure than animals and have their own method of excretion. Plants eliminate some waste through diffusion, during the day surplus oxygen gas that is produced via photosynthesis is expelled through the stomata and carbon dioxide is generally used up during this process. At night however, photosynthesis slows and therefore the carbon dioxide is not used up as quickly as it is produced so it is then released as a waste product.

Plants are able to eliminate waste products by the accumulation of waste in the vacuoles by the aging of the plant leaves; the leaves eventually die and fall off thus removing waste products in the process. Also excretory products such as resins, gums and latex can be expelled as milky or oily substances being forced from the bark of the tree.

Insects have a series of tubules for excretion called Malpighian tubules. Fluid enters at the upper end of the tubules and passes down their entire length. The cells in the tubular walls reabsorb precise amounts of water, salts, and other materials to maintain delicate balance within the insect tissues. The tubules eventually lead to an insect's intestine where waste products are removed. nutrition All living things need nutrients to provide them with the raw materials they need to grow, help them survive, produce new cells, replace old cells and to also help to produce the important chemicals for cell processes. Essential nutrients are vital for those organisms that are unable to produce it for themselves so would need to obtain them from another source. If organisms are deprived of the vital essential nutrients deficiencies could develop. These deficiencies can include plants becoming yellow in colour from the lack of the mineral magnesium that is essential to create chlorophyll which can help to keep the green colour; also humans can develop scurvy if there is a lack of vitamin c within their diet.

Plants obtain their nourishment from the air and soil. They are able to produce basic forms of food, glucose and they are able to obtain minerals via their roots within the soil. This is completed by a process called photosynthesis. Photosynthesis is a chemical process through which plants and bacteria, produce glucose and oxygen from carbon dioxide using only light as a source of energy.

Animals obtain their nutrients through a broad variety of feeding patterns. Many animal species, such as sponges, feed on small particles of food that enter their pores. Other aquatic organisms, such as sea cucumbers, wave their tentacles about and trap food on their sticky surfaces. Mollusks, such as clams and oysters, feed by filtering materials through a layer of mucus in their gills. Other animal species, such as certain arthropods, feed exclusively on fluids. Some animals feed on food masses, and they usually have organs for seizing, chewing, and consuming food. Herbivores are animals that eat plants, while carnivores are animals that eat other animals. Omnivores, which consume both plants and animals, are typified by humans.

Animals will either eat plants directly or will eat other animals that have consumed other plant matter. Animals are unable to chemically convert food into energy so by consuming plant matter, complex substances are then able to be broken down so that energy can then be released as a separate process. conclusion In conclusion, there are various functions that are needed for the existence of life on Earth to take place inside the body of all living organisms. These functions are collectively known as life processes. These life processes are movement, respiration, sensitivity, growth, reproduction, excretion and nutrition.
Living things move in order to survive. Plants move parts of themselves. They move when they are growing.Plants move their roots towards water and towards the centre of the earth. They move their stems and leaves towards light. Animals move to keep themselves safe and to look for food.
All living things reproduce. This means that they make copies of themselves before they die. To be able to reproduce their own kind, animals and plants have to be mature. All living things react to stimuli. This means they are sensitive to changes in their surroundings and react to them. All living things grow. This means they increase their size. They can grow taller. They can grow wider.
All living things need oxygen to stay alive. They use oxygen to turn food into energy. To obtain oxygen from the air, animals and plants exchange gases between themselves and their surroundings.
All living things have to remove the harmful effects of waste products. Waste products can include carbon dioxide, nitrogen and water. To help them to grow and repair, cells of the body need nitrogen. As the cells wear out and new ones take their place, the nitrogen waste goes from them into the blood and must be removed.
All living things feed. They feed to supply themselves with energy. Animals do not make their own food. They feed on other animals and on plants. Animal’s bodies are made up of millions of cells.Animals feed to help them to grow and repair the cells of the body which need nitrogen. Nitrogen is found in certain foods such as meat, fish, beans and peas. Most green plants make their own food. They make their food from the simple raw materials carbon dioxide and water.
If any one of these processes is missing then it would have a substantial effect on the other processes and would potentially contribute to the decrease in organisms as they would not be able to fully function without all seven processes. | |

BIBLIOGRAPHY

Books

Parsons, R., 2007. AS-Level Biology Exam Board: AQA Complete Revision & Practice. UK: Coordination Group Publications

Campton, J., 2012. CCEA Biology AS Unit 1 Molecules and Cells. London: Hodder Education

Applin, D and Pickering, R., 2011. OCR Biology Revision Guide A2. UK: Oxford University Press

Fosbery, R., Stevens I and Gregory, J,. 2008. OCR Revise Biology AS. 2nd ed. UK: Heinemann

Boyle, M., 2008. Student Support Materials for AQA AS Biology Unit 2: The Variety of Living Organisms. London: Harper Collins Publishers

Websites

www.biologymad.com

www.bbc.co.uk/schols/ks3bitesize/lifeprocesses

www.biotopics.co.uk/life/7chars

www.emagister.co.uk/gcse_biology_lifeprocesses

www.revisioncentre.co.uk/gcse/biology/life_processes

www.eriesd.org/lessonplans/lifecycle/animals

www.biology.about.com

www.biology4kids.com

www.s-cool.co.uk/respiration