Biological Processes

The Meaning of Biological Processes

Each organism can regulate its biological processes, such as growth, nutrition, and breathing patterns. In biology, the method of intaking necessary nutrients from food is called assimilation. We "assimilate" our food through physical (chewing) or chemical (Proteins such as Enzymes and stomach acids) means.

Autotrophs, like Plants, "assimilate" their nutrients through Photosynthesis or other inorganic resources. Photosynthesis is a biological process by which Plants use light energy to convert carbon dioxide and water into glucose. Glucose is a simple sugar or carbohydrate that consumers or Heterotrophs can use for chemical energy.

Heterotrophs, like us humans, "assimilate" our nutrients through cellular Respiration. Cellular respiration is the process by which glucose is converted into ATP. ATP, or adenosine phosphate, is an organic compound that gives cells a usable form of energy.

Organic compounds are chemical compounds comprised of carbons bonded to elements, such as hydrogen, oxygen, and nitrogen. Carbon is vital to life because it can quickly form bonds with many other elements, allowing it to be the building block of Macromolecules.

Macromolecules are giant molecules that are formed when smaller molecules bond together.

Biological Processes - Examples

There are many examples of biological processes all around us. Many of these processes occur both inside and outside of your body. Homeostasis, organization, metabolism, Response to Stimuli, Reproduction, and interaction between organisms are all examples of biological processes. Let’s look at two processes you may already be familiar with.

Homeostasis is how our bodies regulate the internal environment to maintain a constant state. This depends on a Negative Feedback loop that triggers a response when our internal environment goes through too much change. One tangible example of this regulation would be sweating. When the core temperature of our bodies rises too high, a signal is sent to your sweat glands to activate. When the sweat evaporates, our skin, and the Blood flowing through it, are cooled and bring down the body's temperature.

Another example of homeostasis would be our bodies' maintenance of Blood glucose levels. Insulin and glucagon are the controllers of our Blood glucose level. After eating, our body produces insulin which will lower Blood glucose levels. When we haven’t eaten for a while, our body produces glucagon, which raises Blood glucose levels. Diabetes is a disease that occurs when this feedback loop is broken in the form of poor Insulin secretion, causing blood glucose levels to spike.

The last example we’ll cover is Reproduction. Every living organism on this planet results from the reproductive process, whether it be sexual or asexual reproduction. Asexual reproduction is when an organism makes a clone or a very similar version of itself without sexual reproduction with another organism. Sexual reproduction occurs when two compatible organisms unite and create a fertilized zygote. This zygote is the offspring of the parents and will carry the genetic material of both parent organisms.

Microbial Biological Processes

Microbial biological processes are processes that microbes need to survive or stay alive. Aerobic bacteria need oxygen to survive, while anaerobic bacteria that do not. There are also facultative anaerobe bacteria that would ideally prefer to grow in the presence of oxygen but don’t require it to survive.

Bacteria can also be grouped by how they obtain nutrients:

Heterotrophs are consumers that receive energy from breaking down complex organic compounds. Examples of heterotrophic bacteria include decomposers and bacteria that rely on aerobic or anaerobic Respiration and fermentation.

Decomposers, or detritivores, are organisms, such as Fungi and bacteria, that break down dead organisms.

Autotrophs are producers that make their energy or nutrients from inorganic sources. Examples of autotrophs are photoautotrophs, which receive their nutrients from light energy, and chemoautotrophs, which receive nutrients from the oxidation of inorganic compounds.

We'll cover photoautotrophs in more detail in the section called "biological processes in plants." As for chemoautotrophs, some of the most important examples are nitrogen-fixing bacteria, which are bacteria involved in the nitrogen cycle.

Nitrogen is essential for living organisms, as it's in the structures of proteins and nucleic acids, such as DNA. DNA, or deoxyribonucleic acid, is the genetic material of living organisms. Nitrogen is also essential as it's considered a limiting nutrient.

Limiting nutrients are nutrients necessary for growth and development of living organisms that are in low supply in the environment. This means that the lack of these limiting nutrients, such as nitrogen, can prevent or limit further growth in ecosystems.

Bacteria play crucial roles in the nitrogen cycle because, even though other living organisms need it, they cannot convert nitrogen gas, or \((N_2\)), into a form that is useful to us.

The stages of the nitrogen cycle are illustrated in Figure 1:

1. Nitrogen fixation: nitrogen gas or atmospheric nitrogen \((N_2\)) is transformed into ammonia \((NH_3)\) by nitrogen-fixing bacteria such as Rhizobium. Ammonia is a usable form of nitrogen that is fixed in the soil or aquatic environments usually.

2. Nitrification: During nitrification, ammonia is transformed into nitrite \((NO_{2}^-\)) and then nitrate \((NO_{3}^-\)) by soil bacteria such as Nitrosomonas. This is because ammonia is toxic to plants and other organisms.

3. Assimilation: During assimilation, plants, fungi, and specific bacteria assimilate or take in mainly nitrate \((NO_{3}^-\)) from the soil. They can sometimes also take in ammonium \((NH_{4}^+)\). Animals get nitrogen into their bodies by consuming organisms such as plants, making them heterotrophs.

4. Ammonification: Ammonification is the process by which decomposers break down dead organisms such as plants and animals. This process results in ammonium \((NH_{4}^+)\) and ammonia \((NH_3)\).

5. Denitrification: During denitrification, nitrate and nitrite are usually converted into nitrogen gas or \((N_2\)). This allows nitrogen to return to the atmosphere. Hence making the process of acquiring nitrogen a cycle.

Figure 1: Nitrogen cycle illustrated. Wikimedia, EPA.

Biological Processes - The Carbon Cycle

The nitrogen cycle isn't the only important cycle necessary for our survival. Another biological cycle that's vital is the carbon cycle.

The carbon cycle is essential as it controls the earth's temperature, makes up vital macromolecules like Carbohydrates, and involves crucial biological processes, such as Photosynthesis and cellular respiration.

The carbon cycle can control the earth's temperature through greenhouse gases.

Carbon dioxide \((CO_2)\) is a significant greenhouse gas, and carbon burning produces it. Without greenhouse gases, our earth would lack warmth and be frozen.

The stages of the carbon cycle are:

1. Plants take in carbon in the atmosphere through photosynthesis. We will go over photosynthesis in the next section.

2. Animals consume the plants causing the carbon to move from plants to Animals.

3. When plants and animals die, they decompose, causing carbon to be let back into the atmosphere. Living organisms can also release carbon into the atmosphere through cellular respiration.

4. Carbon not released into the atmosphere becomes fossil fuels. This is why carbon gets released into the atmosphere when fossil fuels are burnt. The excessive burning of fossil fuels for energy has resulted in global warming.

5. The ocean absorbs carbon from the atmosphere, acting as a carbon sink. This causes the carbon to dissolve in the water.

6. Carbon can also be released into the ocean by weathering rocks. Carbon is usually removed from ocean water when limestone settles on the ocean floor. The limestone comes from marine animal shells and bones. This carbon can be released into the atmosphere usually once the limestone melts.

Figure 2 shows how the carbon cycle works and how much carbon is exchanged. The carbon flux or amounts of carbon exchanged are usually measured in units of gigatons per year or GtC/yr.

Figure 2: Carbon cycle illustrated. Wikimedia, NASA.

Biological Processes in Plants

Plants have their own set of biological processes and some of which they also share with us. Some primary procedures are growth and development, photosynthesis, respiration, and Transpiration.

Photosynthesis is a crucial process, as it releases oxygen as a byproduct. Around 50% to 80% of the world's oxygen, which we breathe, comes from oceanic phytoplankton and marine plants. Although land plants also produce oxygen; for instance, rainforests make around 28% of the world's oxygen.

The green plants not located in water are called land plants or embryophytes. They are terrestrial plants and the plants we think about when we think of plants. Angiosperms, or flowering plants, are the most common land plants. They consist of plants like roses, orchids, daisies, etc.

Marine plants and phytoplankton are distributed over a larger surface area than land plants simply because the ocean covers around 70% of our surface on earth compared to land.

Plants are essential because they provide energy and oxygen to consumers like us. This means that their survival is essential to us. For plants to flourish, they need to be able to grow and develop.

The general process for growth and development in plants is embryogenesis, Seed Germination, the vegetative stage, the reproductive stage, and the ripening stages.

All seeds contain embryos located inside them, and a hard covering called a seed coat protects them.

Seed Germination deals with seed sprouting and occurs when there are favorable light, heat, and water conditions.

• The vegetative stage involves the growth of stems, leaves, and roots. During the vegetative stage, plants also undergo photosynthesis to obtain resources to be ready for the next step.

• The reproductive stage occurs when the plant matures and is prepared to make flowers and fruits.

• The flowering stage is when plants are usually pollinated.

• Ripening is the stage in which vegetables or fruits grow or ripen. They produce these fruits, so animals can eat them and distribute its seed so that the cycle can start over again.

• Transpiration is the process by which water travels through a plant and evaporates from stems, flowers, and leaves.