In this lesson you will get an introduction to what biology is, we will discuss classification of living organisms, competition between living organisms and we will look at how living organisms adapt to their environment.

 

Biology is the study of living organisms. We could define “living” by saying that all living things are made up of cells. A cell is the smallest living thing that can perform all the functions of life. There are hundreds of different types of cells on earth. Some living organisms are made up of just one cell, such as a bacteria, others are made up of millions of cells collected together, such as a human.

 

We can see the difference between something that is dead or non-living from something that is living by its ability to grow and expand in size, undergo metabolism (break down carbohydrates, proteins and fats into smaller units), respond to stimuli (react to something happening around or to them), adapt (change to handle their environment better) and reproduce. Living organisms come in all shapes and sizes. To make studying living organisms easier, we can classify them all into different categories. The categories include:

 

• Plants

• Animals

• Microorganisms

 

But not all plants are the same, and not all animals are the same, and not all microorganisms are the same. We can further categorise each living organism into many other sub-categories.

 

Some plants produce flowers (flowering plants) and some plants do not (non-flowering plants).

 

We’ve all seen the huge variety of animals on the planet. Animals can be categorised into two big categories:

 

                Those with a backbone (vertebrates) e.g. humans, dogs, cats, birds, fish etc

                Those without a backbone (invertebrates) e.g. worms, spiders, beetles etc

 

There are many other differences between the two categories such as:

 

• 2% of animal species are vertebrates, the rest 98% are invertebrates, so there is a lot more diversity in invertebrates than there is in vertebrates. 

• Vertebrates tend to be larger with more developed brains

•  They have a closed blood system

• They have either gills or lungs for respiration

 

These points will be explained more clearly at a higher level, it is just good to be aware of them for now.

 

Other living things include microorganisms such as fungi, bacteria and algae.

 

As you can see, when organisms have similar features to each other, they can logically be placed under the same category. This makes it easier to find evolutionary links/distances, identify an organism, and identify relationships between different species.

 

Organisms are given a universal “scientific name” by an international committee such as The International Committee on Zoological Nomenclature. This makes it easier for scientists in different countries who speak different languages to identify a species. For example, an organism commonly known as the giraffe has a different common name in a different language such as French, but its universal scientific name, Giraffa Camelopardalis, is the same in all countries. This reduces confusion.

 

With advances in DNA technology, we can find new relationships between different species, more information means changes are being made to the classification system. Before DNA technologies were available, animals were classed just on morphological characteristics. Now by combining the two ways of classifying animals we can create a more accurate system of classifying organisms.

 

The two ways to classify living organisms use different classification methods. Those classified using morphological characterisitcs have been classied using "the 5 kingdom" method. The 5 kingdoms are animals, plants, prokaryotae (e.g. Bacteria), Fungi and Protoctista (e.g. Algae). Once an organism has been classified by kingdom they are then further classified by phylum, then class, then order, then family, then genus and finally species. The scientific name of an organism is the genus and species name put together. So thee genus of Giraffa Camelopardalis is Giraffa and the species is is Camelopardalis. Those classified using DNA technology are classified the Three Domain classification system. This system classifies organisms under the three main categories of Ancient Bacteria, Bacteria and All organisms with a nucleus.

 

Competition

In order to survive, individual organisms require certain resources that they get from their environment. Sometimes there is not enough of these resources for all the individual organisms so they must “compete” for them. Plants will compete for resources such as light, minerals, space and water. Animals will compete for things such as food, water, space and mates. In a larger population there will be more competition than in a smaller population if the same amount of resources are available. Competition can happen between members of the same species, such as grizzly bears competing with each other to get the most fish. Or it can happen between members of different species, such as poppy competing with Barely for space, water, light and nutrients.

 

 

Adaptation

Adaptation is the process of how a living organism becomes better suited to the environment it lives in. An example of how similar animals have changed to suit the conditions they live in is the desert fox and the artic fox. The table below shows a comparrison between the two.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Examples of adaptations in other living organisms can involve:

 

• Behavioural adaptations: e.g. desert mammals tend to only come out at night when it is cooler (nocturnal animals).

• Some plants have brightly coloured flowers to attract insects which will pollinate them.

• Cacti have spikes in order to keep animals from eating them as well as reduce water loss.

 

Invertebrates that live in freshwater have certain adaptations that allow them to live in water:

• Some travel to the water surface to collect air to get oxygen. Freshwater invertebrates such as adult beetles may have "spiracles" under their wings which are able to absorb air to obtain oxygen from when they are at the surface of the water. These invertebrates will have to continue to travel to the surface regularly for oxygen as they can't collect enough to sustain themselves.

• Other creatures can use diffusion to obtain dissolved oxygen in the water without having to go to the surface. Diffusion will be discussed in later lessons.

• A water scorpion recieves its oxygen using a tube that draws down air.

• Chironomid larvae are able to store oxygen for when oxygen may be lacking in the water so it doesn't suffocate when there is not enough oxygen in the water.

• The rat-tailed maggot has a telescopic siphon that it can use as a snorkel to obtain oxygen from the water surface even though it reminas at the bottom of the water.

• By producing bubbles either outside them or inside them they prevent themselves from sinking to the bottom of the water. A diving beetle produces them outside where as a phantom midge produces them inside. It does this by using the air sacs at either end of it's body. The air sacs are the adaptation.

• Those living on the surface such as pond skaters use surface tension to prevent them from sinking. They are able to do this because they are very light-weight. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Questions:

 

1. What is biology?

2. What is a cell?

3. What 2 main categories can plants be divided in to?

4. What 2 main categories can animals be divided in to?

5. Give an example of a microorganism.

6. Give a reason why we classify living organisms.

7. Why do we give living organisms a universal scientific name?

8. What two methods can we use to classify living organisms?

9. What are the 5 kingdoms?

10. What are the 3 domains?

11. Give an example of a typical adaptation found in desert animals.

12. Give an example of a typical adaptation found in artic animals.

13. Give 3 examples of resources that plants compete for.

14. Give 3 examples of resources that animals compete for.