4.1.1.2 Animal and plant cells Section 4.2.1 Principles of organisation, is covered at KS3 so the content could be recapped now, rather than later in the course. Most animal cells have a nucleus, cytoplasm, membrane, mitochondria and ribosomes. Plant and algal cells also have a cell wall and often have chloroplasts and a permanent vacuole. Functions of the organelles. Required practical: Microscopy Use a light microscope to observe, draw and label a selection of plant Label diagrams of animal and plant cells. Describe the function of the main organelles. Prepare slides of plant and animal cells and describe the procedure. Correctly use a microscope to observe cells under different magnifications. Describe the order of size of: cell, nucleus, chromosome and gene. 2 Recap cell structure from KS3 by drawing an animal and a plant cell on mini white boards. Class to vote on which are the best and why. Display diagrams of a plant and animal cell - students spot the difference between the two. Label diagrams of plant and animal cells. Complete a card sort to match the organelle to the function. Construct a table to compare animal to plant cells. Include organelles and processes that they carry out (eg respiration, photosynthesis and protein synthesis). Prepare slides and observe using a microscope. video clips on plant and animal structures. Make a plant or animal cell model. Prepare slides of epidermis, rhubarb epidermis, cheek cells, spirogyra, moss etc.Observe under a microscope. Make labelled drawings Model plant and animal cells. Observation activity materials: microscopes slides coverslips forceps mounted needles cotton buds iodine solution methylene blue onion rhubarb spirogyra moss. National Stem Centre – Cells and organ systems Video clips:
Topic can be delivered after Cell differentiation, or later in the course as the technology involved relates to 4.6.2.5 Cloning. Stem cells are unspecialised cells that can differentiate to form many different types of cells. Stem cells from human embryos and adult bone marrow can be cloned and made to differentiate into different cells, eg nerve cells. Stem cells may be used to treat paralysis and diabetes in the future. In therapeutic cloning an embryo with the same genes as the patient is produced. Cells from Describe where stem cells can be found in animals and plants. Describe in simple terms how nerve cells genetically identical to a patient could be obtained. Describe how stem cells could be used to help treat some medical conditions. Evaluate risks and benefits, as well as the social and ethical issues concerning the use of stem cells from embryos in medical research and treatments. Stem cells in plants – see 4.6.2.5 Cloning. the stem cell story at Europe’s stem cell website. Tell the story of Christopher Reeve (show photos of Superman or watch the Superman trailer) and get students to suggest how stem cells could be used to treat other people with paralysis. Provide a circus of different stem cell related articles which cover current uses, potential uses as well as pros and cons. Students circulate to complete a summary table on uses, pros and cons. Watch the Teacher’s TV video about the use of stem cells and Parkinson’s treatment. Students have different roles and must prepare and present their arguments in favour of or National Institute of Health – Teachers TV:
this embryo will not be rejected by the patient. Risks eg transfer of viruses, associated with the use of stem cells in medicine. Stem cells from meristems in plants are used to produce clones quickly and cheaply. against the use of embryonic stem cells (eg doctor, person with diabetes, human rights activist). 4.1.1.1 Plant and animal cells are eukaryotic cells which have a membrane, cytoplasm and a nucleus. Bacterial cells are prokaryotic cells. They are smaller than eukaryotic cells and have a cell wall, membrane and cytoplasm, but do not have a nucleus. Their genetic material is a single loop of DNA or Identify plant, animal and bacterial cells and classify them as eukaryotic or prokaryotic cells. diagrams of bacterial cells. Describe the differences between eukaryotic and prokaryotic cells in terms of structure and size. 1 Develop an argument for and against bacteria cells to be classified as plants or animals. Label a diagram of a bacterial cell. Construct a table to compare the structure of plant, animal and bacterial cells. Use Teachit interactive resources about cells of animals, plants and bacteria. Observe images of different types of bacterial, plant and animal cells and classify them as plant, animal or bacterial; eukaryotic or prokaryotic cells. Assessment material:
several small rings of DNA called plasmids in the cytoplasm. 4.1.1.5 Microscopy An electron microscope has a much higher magnification and resolution than a light microscope, so it can be used to study cells in much finer detail and show organelles. Describe the differences in magnification and resolution of light and electron microscopes. Explain how electron microscopy has increased understanding of organelles. Calculate the magnification of a light microscope. Carry out calculations using the formula: Rearrange the equation to calculate image size or magnification. Convert values for the units: cm, mm, µm and nm. 1 Use a variety of resources to research the differences between a light microscope and an electron microscope. Use online materials to make a display of cell images from a light microscope and from an electron microscope. Write a newspaper article entitled: ‘Microscope…..the best invention ever!’ where students explain the significance of the microscope and discuss what the world would be like if microscopes were never invented. Calculate the real size of microscope images, and convert units as appropriate. Rearrange the equation to calculate a different unknown. Use online and printed materials to calculate the real sizes of cells and structures. Limited to the differences in magnification and resolution. Extension work Use a microscope with graticule to measure cells and calculate their real size. Observation activity materials: microscope graticule prepared slides calculator. 4.1.1.6 Culturing microorganisms Know that bacteria multiply by simple cell division. 1 How many bacteria be made during the lesson if there was: Preparation of inoculating plates.
Spec ref. Summary of the specification content Learning outcomes What most students should be able to do Suggested timing (hours) Opportunities to develop Scientific Communication skills Opportunities to develop and apply practical and enquiry skills Self/peer assessment opportunities and resources Reference to past questions that indicate success 4.1.2.1 Chromosomes Chromosomes are found in the nucleus. They are made of DNA. Each chromosome carries a large number of genes. In body cells chromosomes are found in pairs. Describe what a chromosome is and where chromosomes are found in the cell. 0.5 Draw and label diagrams showing cell, nucleus, chromosome and gene. Consider the scale of these structures. Observe images of human karyotypes as seen under the microscope and arranged into pairs. Students could attempt to arrange chromosome images into pairs. This could be extended to show karyotypes of males, females, Down syndrome and Turner syndrome. Discuss the differences and suggest what the possible reasons and consequences of these differences are. Research on chromosome abnormalities. Observe chromosomes using bioviewers or prepared slides. Observation activity materials: microscopes prepared slides bioviewers. National Human Genome Research Institute: 4.1.2.2 Mitosis and the cell cycle This topic could be left until later and taught with Asexual reproduction in 4.6.1. Describe simply how and why body cells divide by. Knowledge and understanding of the stages in mitosis are not required. Draw simple diagrams to describe mitosis. 1 Watch video clip showing mitosis. Discuss how organisms grow and relate this to cell division. Observe mitosis in Use bioviewers or root tip squashes to show chromosomes and mitosis. Model mitosis. Video clip: (first part of Mitosis and meiosis)
Spec ref. Summary of the specification content Learning outcomes What most students should be able to do Suggested timing (hours) Opportunities to develop Scientific Communication skills Opportunities to develop and apply practical and enquiry skills Self/peer assessment opportunities and resources Reference to past questions that indicate success 4.1.3.1 Diffusion Substances can move into and out of cells across membranes by diffusion. Definition of diffusion and factors affecting rate. Oxygen, carbon dioxide and urea passes through cell membranes by diffusion. Single celled organisms have a bigger surface area to volume ratio than multicellular organisms, so transfer sufficient substances across their surface. Multicellular organisms require specialised organ systems to Define the term ‘diffusion’. Explain how temperature, concentration gradient and surface area affect the rate of diffusion. Give examples of substances that diffuse into and out of cells. Calculate and compare surface area: volume ratios. Explain how the small intestine and lungs in mammals, and roots and leaves in plants, are adapted for exchange of substances. Describe and explain how an exchange surface is made more effective. 2 Observe demos and suggest explanations: Time how long it is before students can smell a perfume placed in a corner of the room. Is the rate of diffusion different for different gases? Use concentrated ammonium hydroxide and hydrochloric acid in a large glass tube. Does temperature affect the rate of diffusion? Fresh beetroot placed in iced water and warm water. Record observations and suggest explanations. Watch a video or computer simulation of diffusion on BBC or McGraw-Hill website. Role play diffusion in gases and liquids at different temperatures and concentrations. Choose investigations as appropriate: potassium permanganate in beaker of water; potassium permanganate on agar investigate diffusion of different acids and alkalis through agar investigate rate of diffusion of glucose through cellulose tubing use digital microscope to observe diffusion of particles in milk or yogurt solution. Model diffusion. Observe slides or micrographs of villi, alveoli, root hair cells and leaves. Demo materials: strong perfume concentrated NH4OH concentrated HCl gloves mask forceps cotton wool long glass tube with strips of damp litmus along length beetroot beakers kettle ice two gas jars of NO2 two empty gas jars. Optional demo materials:
exchange sufficient substances. Factors affecting the effectiveness of an exchange surface. Observe micrographs of exchange surfaces in plants and animals. Make drawings and relate structure to function. Produce a mind map to summarise diffusion and exchange surfaces. Calculate surface area: volume ratios for different sized objects or using data about organisms. beaker of water pot perm crystals forceps agar in test tube or agar plates impregnated with UI solution cork borers solutions of acids and alkalis beakers cellulose tubing glucose solution timers test tubes Benedict’s solution and water bath or glucose test strips. Activity: McGraw-Hill Higher Education: 4.1.3.2 Osmosis Define the term ‘osmosis’. 2 Set up a simple osmometer at the start of the lesson and Make predictions with explanations. Demos:
Water may move across cell membranes by osmosis. Osmosis is the movement of water from a dilute solution to a more concentrated solution through a partially permeable membrane. Required Practical: Osmosis Investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue. knowledge of osmosis to unfamiliar situations and make predictions. measure how far the liquid in the capillary tube rises during the lesson. Explain the movement of water molecules as a special type of diffusion through a partially permeable membrane. Predict and explain what will happen to cellulose tubing bags filled with or sugar solution, placed in beakers of water or sugar solution. Observe and explain the effects of water and concentrated salt solution on cells of onion/ beetroot/ rhubarb. Use a model to show osmosis or get students to make a model. Watch a computer simulation of osmosis in plant and animal cells. Watch a video clip of osmosis in blood cells. Investigate the effect of water and concentrated salt solution on onion/ beetroot/ rhubarb cells. Model osmosis. 1) Cellulose tubing filled with conc sugar solution attached to capillary tube held in clamp, beaker of water. 2) Four beakers (two of water and two of sugar solution); four cellulose sausages (two of water and two of sugar solution). Observation activity materials: living plant cells: onion/ beetroot/ rhubarb microscopes slides coverslips water concentrated solution pipettes blotting paper. Model materials: plastic box plasticine for membrane