1.1.1 Characteristics of Living Organisms

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[Audio] We will look at the concept of classifying organisms into species, which is based on their shared features. All mammals, for example, have bodies covered in hair, feed their young from mammary glands, and have external ears. Understanding how organisms are classified gives us insight into the diversity and complexity of life on Earth..

[Audio] We will take a look at the binomial system, a system developed by the Swedish naturalist Linnaeus which allows us to classify living organisms. Binomial names are comprised of two parts: their genus, always capitalized, and their species, written in lowercase. Additionally, there is a sequence of classification which includes kingdom, phylum, class, order, family, genus, and species. By understanding this classification system, we can gain a better understanding of the world around us..

[Audio] Examining the concept and uses of classification systems can help us understand the order of classification. To help with this, a mnemonic like KING PHILIP CAME OVER FOR GRAN’S SPAGHETTI can be used. This provides an easy way to remember the order of classification..

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[Audio] An example of a dichotomous key is a tool used to help identify organisms. It works by asking a series of questions, each with two possible answers. By working through the questions, you can determine which organism is being examined. This slide will take a closer look at the example..

[Audio] Mastering the use of a simple dichotomous key is an essential topic for the IGCSE Biology CIE exam. In order to answer exam questions related to this, it is important to understand how to use and interpret the key. Rather than just focusing on learning how to construct it, make sure to familiarize yourself with how to employ it. Being confident in applying this knowledge for the exam is key to successful results in related questions..

[Audio] We will discuss how classification systems reflect evolutionary relationships. We will first look at traditional biological classification systems and why they have their limitations. Then, we will explore how scientists use DNA to classify organisms, to understand more accurately their evolutionary relationships and improve the classification process. Let's begin our exploration..

[Audio] We are now focusing on the classification of living organisms, which are separated into five kingdoms: animals, plants, fungi, protoctists and prokaryotes. Animals are multicellular organisms with cells that contain a nucleus but no cell walls or chloroplasts, and they feed on organic substances made by other living things. Plants have multicellular cells that contain a nucleus, chloroplasts, and cellulose cell walls, and they all feed by photosynthesis. Fungi, protoctists and prokaryotes all possess their own unique characteristics..

[Audio] We are looking at a typical plant cell. Composed of many components, such as a cell membrane, nucleus and mitochondria, the cell membrane acts as a barrier to separate the inside of the cell from the outside environment. The nucleus is the control center, containing DNA and responsible for regulating the cell’s functions. The mitochondria act as the powerhouse of the cell, providing energy for the cell’s activities. In the next slides, we will learn further about the structure and function of plant cells..

[Audio] We'll start by looking into the 5 classes of vertebrates. All vertebrates have one common feature - a backbone - but each class has distinct features that separate them from the others. We'll be discussing the features of each class and how they differ from one another. To further our understanding, we will also be looking at a table of vertebrates. So, let's dive in..

[Audio] Understanding the characteristics and classifications of living organisms is key to understanding how organisms interact with each other. Invertebrates are organisms without a backbone, and can be further classified by their presence or absence of legs into various classes of arthropods. This table gives a summary of the various invertebrate classes..

[Audio] Taking an in-depth look at the classification of arthropods, we will discuss the different types of arthropods and the characteristics that define them. Reviewing the various classification systems used to classify arthropods, we will explore the features of arthropods and how they are used to identify different species..

[Audio] We will look at the five kingdoms of living organisms and their common features. Fungi are typically multicellular, containing nuclei and cell walls, which are not composed of cellulose. They do not photosynthesize but acquire nutrients through saprophytic or parasitic means. Protoctists are mainly unicellular, have a nucleus and some may have cell walls and chloroplasts. This allows some to photosynthesize, while others to feed on organic matter created by other living things. Exploring the features of fungi and protoctists in more detail is our next step..

[Audio] We will be looking at the characteristics and classification of living organisms, including two examples of protoctist cells and the main features of all Prokaryotes, such as bacteria and blue-green algae. These cells often have cell walls, cytoplasm, but no nucleus or mitochondria. We will also be looking at a typical bacterial cell. As we cover this material, jot down any points of interest and questions that arise in the ‘Your Notes’ section..

[Audio] We will be discussing the plant kingdom and the key characteristics of ferns and flowering plants. Ferns are easily identified due to their fronds which are modified leaves, and they reproduce by spores found on the underside of the fronds. Flowering plants reproduce sexually through flowers and seeds; the seeds being produced inside the ovary found at the base of the flower. There are two groups of flowering plants – monocotyledons and dicotyledons, and wheat plants are an example of monocotyledons. All plants contain chlorophyll, the pigment responsible for absorbing energy from sunlight to support the process of photosynthesis. For more detailed information, visit savemyexams.co.uk, a great resource for revision notes, topic questions, and past papers..

[Audio] We have been discussing the characteristics and classification of living organisms, with one example of a dicotyledon being the sunflower. To distinguish between monocotyledons and dicotyledons, petals in multiples of 3 and parallel leaf veins indicate monocotyledons, while petals in multiples of 4 or 5 and reticulated leaf veins indicate dicotyledons. This lesson has hopefully been helpful in understanding the differences between these two groups of organisms. To further practice and enhance your understanding on this topic, visit savemyexams.co.uk..

[Audio] We have covered some fundamental concepts about the characteristics and classification of living organisms - discussing the characteristics of living organisms, the concept and uses of classification systems and the features of organisms. We have also examined the two differences between monocotyledons and dicotyledons and the structure of a typical virus. I hope you found this information helpful and found it easy to understand. Thank you for your attention..