KS3 Science Cells
Cells Key Words Task Write a definition for each of the key words listed below Key words Microscope Plant cell Animal Cell Nucleus Cell Membrane Cytoplasm Cell wall Chloroplasts Mitochondria Vacuole Specialised cell Unicellular organism 2
1. The Microscope Task Label the microscope using the key words provided Key words Eye piece Focusing knob Stage clamps Mirror/light Stage Objective lenses Using a Microscope Use your knowledge of cells and the microscope to write a method for a year 7 pupil explaining how to look at onion cells under a microscope. Remember to explain how to prepare you slide first. Use as many key words as possible. 3
2. Plant and Animal Cells Task Label the plant and animal cell: Cell membrane Cytoplasm Nucleus Chloroplasts Vacuole Cell wall Both cells have: Only plant cells have: 1. 1. 2. 2. 3. 3. Which part of both cells passes on information to new cells? Which part of the plant cell absorbs the energy form the sun and uses it in photosynthesis? Which part of the plant cell is made of cellulose and helps the cell to keep its shape? Which part of the cell is a jelly like substance where chemical reactions take place?. 4
3. Specialised Cells Task Cells may be specialised for a particular function (job). Their structure will allow them to carry this function out. Read through the information below, highlight any adaptations that allow the cell to carry out a particular function and use this information to complete the table Specialised Cells Information All living things are made of cells, so there are lots of different types of cells. Every cell is specialised to do a certain job and so we say cells are SPECIALISED. Sperm cell Sperm Cells are very important as they are needed to make a new human. This is made by the father and its job is to find and fuse with an egg cell. Its long tail and small, streamlined body help it swim quickly. It also has lots of mitochondria, which provide energy to allow the sperm to swim to the egg. The head of the sperm cell contains genetic information and an enzyme to help penetrate the egg cell membrane Egg Cell These cells are sometimes called ovum. They are the biggest human cell and they contain lots of nutrients (food) that a developing baby will need. Ciliated Epithelial Cell These cells line the respiratory (breathing) system, and are designed to stop lung damage. They have tiny hairs called cilia which trap any dust or bacteria that try to enter. The hairs help to sweep dust and bacteria out of the system, to prevent them getting into the lungs, where they could cause problems. They have lots of mitochondria, to provide energy for the sweeping hairs. 5
3. Specialised Cells Specialised Cells Information Continued Red Blood Cells Blood is the human transport system. It flows around your body all the time and it will only stop when you die. It is pushed around the body by your heart. Even though blood looks like a very simple red liquid, it is made up of several different types of CELL. Each type of cell in the blood has a certain job to do; they are adapted to their precise job, so we say they are SPECIALISED CELLS. Red blood cells are designed to carry oxygen around the body. Without oxygen you would die. Red blood cells are shaped like a flattened disk- kind of like a refresher sweet! They are unique because they have no nucleus. They have a large surface area and being flattened and having no nucleus gives them more oxygen space to carry oxygen, making them good at their job. Palisade Cells Plants are special because they can make their own food. This process is called photosynthesis and it happens in the leaves. It is the job of the cells that make up the leaves to do the photosynthesis. A palisade cell from a leaf is shown below. Most leaves are green. There are special structures in palisade cells called chloroplasts, which contain chlorophyll, needed for photosynthesis. It is these that give the leaf the green colour. Palisade cells contain many chloroplasts so that they can trap sunlight needed for photosynthesis, so that the plant can make its own food. Their cell wall helps them keep their shape. Root Hair Cells Plants need water and nutrients from the soil to grow. The roots take water and nutrients from the soil for the plant. You might have noticed that plant roots are normally white. This is because the cells that make up the roots do not have chloroplasts. A root cell is shown below. This cell is called a root hair cell because it has long part that looks a bit like a hair. The hair gives them a large surface area to take in or absorb) more water and nutrients from the soil. The more nutrients the plant can get, the faster it will grow. Root hair cells have very thin cell membranes which also make it easier to absorb things from the soil. 6
3. Specialised Cells Complete the table: Diagram of cell Function (Job) Adaptation Sperm cell Egg cell Ciliated epithelial cell Red Blood cell Palisade cell Root Hair cell 7
4. Unicellular Organisms Task Read through the information about unicellular organisms and use this to complete the questions = Unicellular Organisms Information Amoeba Amoeba s are tiny single-celled organisms which need to be viewed using a microscope. There are many different species, but the biggest is only 1 mm across. Amoeba s have pseudopods or false feet. These are produced when the amoeba changes its body shape and help it move around. Amoeba s eat bacteria, algae and plant cells. They eat by surrounding their prey using their pseudopods, forming a bubble-like food vacuole which digests the food. Contractile vacuoles are used to expel wastes and excess water. Bacteria Bacteria consist of only a single cell each, whereas each one of you is made up of about 10,000,000,000,000 cells! If there is just one of them, we call it a bacterium. Bacteria have many different shapes. Some have 'tails' (called flagella) that let them swim. They rotate their flagella like tiny propellers to move themselves through liquids. Bacteria can be found almost everywhere! Bacteria live on or in just about every material and place on Earth, from soil to water to air, and from your body to the North Pole to the Sahara desert. Euglena Euglena are single-celled organisms which live in water. They have chloroplasts which they used to make their own food. They can however also absorb food from their environment. An eyespot, like it s name suggests, is used to see light and help guide the euglena (with the use of their flagella as a propeller) towards patches of sunlight to maximise their rate of photosynthesis and therefore food production. Fungi Fungi are usually bigger than bacteria. If there is just one of them, we call it a fungus. Fungi are more like animals than plants. For one thing, fungi cannot make their own food like plants do, but instead they eat other organisms, as animals do. Individual fungi don t move around. But they can spread by making tiny spores (a bit like seeds) that are carried by wind and rain and grow into new fungus cells when they land. With fungi, there are good guys and there are bad guys. Some make our food go mouldy, and some cause diseases. But they also break down dead plants and animals, keeping the world tidier. We use 8
4. Unicellular Organisms Amoeba Cytoplasm Read Amoebas have projections called pseudopods. These are used to help the amoeba around. Nucleus Amoeba s are a type of cell because they contain a Cell membrane Pseudopod nucleus, cytoplasm and have a. Bacteria Cell wall Cell membrane Cytoplasm Flagellum DNA Some bacteria have tails called flagellum. These are used to help the bacteria around. The DNA of bacteria is not found within the. Instead it is floating around in the. An example of a bacterium is. Euglena Euglena are not plant cells even though they contain chloroplasts. This is because they do not have a or a Nucleus Chloroplast Eyespot Flagellum Cell membrane. Euglena have an eyespot which is used to detect. This helps it find sunlight to move towards and therefore make food in their by photosynthesis. Fungi Food storage granule Nucleus Cell membrane Cell wall Vacuole Cytoplasm Like bacteria, fungi are a type of microbe. They cannot make their own food, but eat organisms instead. They store their food in. Fungi cannot move. They spread by making tiny that are carried by and rain and grow into new fungus cells when they land. 9
5. Multicellular Organisms Living things are organised into systems. Each specific cell is grouped with other cells similar in structure and function to form tissues and ultimately organs: Cells are the basic units of life Groups of cells work together to form ssues Groups of ssues work together to form organs Tasks Complete the table below by naming the organs a) to e) and for each one state which system they are included in A) Le er Organ System C) A B C D E F) D) B) E) F What do we call a part of the body with a special function? What do we call a group of organs which work together to carry out a particular function? 10
5. Multicellular Organisms Tasks Match the organ in box A with the function in box B. 1). 2). 3). 4). 5). 6). A B 1) lungs A) to provide informa on about the environment 2) brain B) To take oxygen in and remove carbon dioxide from the 3) stomach C) to cause movement 4) kidneys D) to con6trol and organise the body s ac vi es 5) muscles E) to digest (break down) food 6) sense organs F) to purify the blood and remove waste products State the name of the organ system that contains the brain, optic nerve, nerves and spinal cord State the name of the organ system that contains the gullet, stomach, large intestine and small intestine State the name of the organ system that contains the heart, arteries and veins. 11
Summary questions Tasks Answer the summary questions 1. What part of the microscope do you clip your slide onto?... 2. What do the focusing knobs on a microscope do? 3. What is an organism? 4. What are the seven life processes? 5. What do chloroplast do? What sort of cell would you find them in? 6. Explain the meaning of: a) tissue b) organ. Give and example of each 7. Give an example of an organ system 8. What is diffusion? 9. Give two examples of substances that move into or out of cells by diffusion. 10. What is a unicellular organism? Give an example 12