Big Ideas and Activities of Life

Each of us start off life by making simply observations.

From these observations we begin to associate observations with ideas, for example: something which is round, becomes a thing known as a ball.

Soon through more observations, we learn to distinguish different types balls.

Likewise, given the task of trying to define what is going on by observing life, a biologist has the choice to view this problem from a variety of perspectives. One can link observations to either big ideas such as “this thing shows features that make it a ball” or look more closely at the organism and examine the individual object’s properties, such as defining what type of ball it may be. In study of biology, one can also choose to look at a biological problem from a microbiotic level ( from a molecular or microscopic level) or a macrobiotic level ( from groups of organisms, populations and ecology). An even similar question could be to ask whether you are looking at properties associated with an individual organism or properties associated with a group of organisms and the environment these organisms are living in. The task remains the same, observations are made and then associated with concepts. From this process, biology attempts to understand the processes of life by forming a matrix, created from the association of concepts to observations.

If you are examining activities of organisms or population and ecology, it is useful to frame your inquiry using six “big” ideas within biology. You can use these six big ideas or concepts in order to make some sense of your observations.

Big Ideas in Biology: ( MacMillan 1985)

• Unity and Diversity

Prior to new techniques in gene therapy, one of the unifying features of organisms belonging to the same “species” was restrictions due to the ability to interbreed amongst each other. Likewise, the lack of breeding created a diversity amongst species. An example of this idea could be to compare cats and kangaroos. It is difficult to breed a cat with a kangaroo. In natural conditions, it is probably impossible. Yet if we compare the two species, looking at distinct properties, we can classify both species as mammals. Further observations of cats and kangaroos could provide enough data that even Sylvester the Cat could define some differences. Both animals have tails and can hop but sheer size and the presence of a pouch could be used to show a distinct difference. The unifying features can be based upon anatomy or activities of life, the diversity may be due to behavior, anatomy or biochemistry. The fun thing about this idea is that it may offer solutions to paradoxical situation. By attempting to see how patterns and properties can be used to explain how all living things may be connected, one can also discover attributes that make something unique.

• Interactions:

A living thing reacts to its environment. This reaction could be movement or a response or perhaps a lack of a response. This interplay between the environment and the organisms opens up an interpretations of how organism interact with their environment. Interactions could be viewed as simply responses to a chemical floating in the air to an exotic mating ritual. Interactions could also be classified as how an organism reacts to factors which are not biological. For example: Abiotic factors such as temperature can also affect how an organism may interact with its environment. To get a feel for this idea, imagine waking up on a cloudy day in February verses a sunny day in July.

Consider the following…

How well you seize the day may be dependent on how you interact with your environment. If you see things as they are in the present tense is there anything else to sense?

• Relationships to Structure and function:

Lets go back to our example of the cat and the kangaroo. Both of these organisms have tails, showing a similarity in structure but each uses their tails for a different function. Early naturalist, viewed living things from a structural point of view. From these observations, some relationships regarding the purpose of structures of linked to an idea known as adaptations. An adaptation could be viewed as a structure that allows an organism to survive within the environment they were living in. The idea of structure and function brings forth an important point. If you label a structure being “a wing” , then it either shows similarities in structure or function. For example, homologous structures may appear similar in structure but have different function ( like the wing of a bat and the hand of a human). Likewise, something could have an analogous function but have a different structure ( such as a wing of an insect and the wing of a bird). By comparing both structure and function, biologist are able to speculate possible genetic, ecological and evolutionary relationships.

• Continuity of life:

The complete story of how traits pass from one generation to the next, was still a mystery until Gregor Mendel and his peas got into the game. The concept of continuity is similar to considering a biological form of history. Information is passed from one generation to the next. Processes linked to this exchange of information can be viewed as being associated to continuity of genetic information. Is all that we are linked to our inherited biochemical information? Are brains biochemically wired to think a specific way? Is there a genetic limit to how the human body can change? These are some of the interesting questions that still remain to be answered.

• Homeostasis:

If we look at the roots of this word, we can infer that it means keeping things balanced. Imagine that within each living thing, there are countless interacting chemicals and a variety of stimuli. Each cell must be able to maintain a balance of energy, water, nutrients and waste as well as some how monitor the ratio between surface area to volume. Processes linked to this process of regulating internal factors are linked to the idea known as homeostasis. As an organism increases from being single celled to organ systems, the task of homeostasis becomes more dependent upon interactions between cells, tissues, organs and systems. This is a key concept to grasp, not only because balance is an amazing feat but also because a large portion of the Biology 12 curriculum revolves around this concept!

• Change with time:

If we view life as a process through time, from the basic cell to the more complex organism, the question arises as to where and how that process came about. Biologist attempt to answer these questions by proposing relationships between direct and indirect evidence that can show possible origins of species. Evidence such as fossils and geological dating can be used as direct evidence, similarities in   embryology, biochemistry or structures have been proposed as indirect evidence. Theories have been linked to this process and remain as such.

Now, let’s change our point of view. Let us suppose that you are looking at the individual organism. How you can start to frame your inquiry so that your questions are related to “the activities of life”.

Activities of life:

• Reproduction

An organisms can only get so big before it bursts. Imagine a balloon expanding with air. At that point, the ration of surface area to volume becomes imbalanced. Put basically, there is too much stuff inside the cell in comparison to the membrane which hold all the stuff inside. So the cell must copy and divide it’s contents. Reproduction can either be done with or without a partner, or asexually or sexually. The challenge is to copy all the genetic material and divide the cellular contents. Within this activity of life is also the question of how traits are exchanged or inherited and so we have a connection with the ideas of genetics.

• Locomotion

There is an old military quote that goes..” If it moves, salute it, if it doesn’t move…paint it”. Well every living thing moves and so the question of how to acknowledge or “salute” that event goes under the heading of locomotion. The notion of movement also includes energy. Remember your physics? Energy is linked to motion, so the questions for a biologist can then focus to areas such as kinetics and nutrition. For example: If a creature has no muscle tissue, does it mean that it uses less energy?

• Metabolism

If an organism moves, then it needs a means to both obtain energy and a way to chemically convert specific compounds into other molecules. Organic compounds can range from simple compounds such as water to elaborate molecules such as proteins and nucleic acids. The unifying factor is that the sum of all these chemicals reactions can be placed into the category of metabolism. Molecules within an organism can be fabricated or synthesized or they can be broken down, or decomposition. An organism can either get is energy from either making it via processes such as photosynthesis or by consuming other organisms. If you make your own energy, you are an “autotroph”. If you seek out energy from an alternate source, you are a

“heterotroph”. The activity of metabolism is closely linked to all the other activities of life. In fact, growth, reproduction, and even responding to a stimulus all require one thing in common..energy. Heh this could be a great trick question in an exam eh!

• Repair and maintenance

This activity is closely linked to the concept of homeostasis. If something is out of balance, it need to be fixed. This repair can be a process of replacing a molecule within a membrane to regenerating a whole limb. What other activities of life do you think would be associated with this activity?

• Growth

What is the difference between repair and growth? Repair is replacing something that has been lost. Remember if it is broken fix it. Growth is “an increase in the amount of living material in an organism”. Growth is not always continual nor is it linear. Growth may vary to due input of energy or metabolism. Remember that trick question? If all these terms and concepts are confusing you, fear not…confusion is the sign of growth!

• Response to a stimuli

Reality…what a concept! How an organism senses its environment is a linkage to how the organism reacts to that environment. The notion of sense does not require complex organs or even a brain. Stimuli which an organism can respond to can either be non living factors such as temperature, light, or non organic compounds ( these are abiotic factors). If the stimuli is another living thing or chemicals created by living things then the stimulus is a biotic factor. The only thing that is constant within living systems is change. An organisms response to that change can be immediate or over a period of time. In some cases, the organism may even “learn” not to respond. Now my final question is: How do you chose to respond to all this written information!