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1. Slide 1: Science Interactive LTD Copyright 2005 Science Interactive LTD Multimedia CD-ROM for PC is a collection of 38 units totalling over 1150 PowerPoint slides matched to current single and double Science GCSE syllabuses. Each unit covers a wide range of different delivery and learning styles, offering an exciting way to involve your pupils during lessons or revision sessions. All styles of teaching and learning are supported through use of high quality images, graphics, challenging exercises and questions. Units can be used in the classroom via an interactive whiteboard, data projector or used during individual study via a PC or school network. Full users’ licence is available under our ‘comprehensive package’ or lessons can be purchased separately. Science Interactive LTD. PO BOX 50764 LONDON NW6 9AT email: sales@science-interactive.co.uk web: www:science-interactive.co.uk GCSE SCIENCE Unit 1: The Digestive System Unit 20: Crude Oil and its Products Unit 2: The Circulatory System Unit 21: Rock Cycle OCR Unit 3: Healthy Body and Immunity Unit 22: Elements, Molecules and Compounds EDEXCEL AQA Unit 4: The Respiratory System Unit 23: Ionic and Covalent Compounds Unit 5: Nervous System and the Senses Unit 24: The Halogens, their Uses and Compounds Unit 6: Human Homeostasis Unit 25: The Noble Gases, their Properties and Uses Unit 7: Hormones and the Endocrine System Unit 26: Rates of Reaction Unit 8: Drugs and Bad Body Maintenance Unit 27: Energy Unit 9: Photosynthesis in Green Plants Unit 28: Generating Electricity and its Domestic Use Unit 10: Water Transport in Plants Unit 29: Electricity Unit 11: Flow of Energy and Elements through the Environment Unit 30: Light and the Electromagnetic Spectrum Unit 12: Mitosis and Meiosis Unit 31: Radioactivity Unit 13: Inheritance and Selection Unit 32: Newton's Forces and the Effects of Forces Unit 14: Evolution and Human Impact Unit 33: Earth and Space Unit 15: Genetic Engineering Unit 34: The Earth and Plate Tectonics Unit 16: The Periodic Table and its Elements Unit 35: The Alkaline Earth Metals Unit 17: The Alkali Metals Unit 36: Sound and Hearing Unit 18: Metals and their Properties Unit 37: Natural Forces Unit 19: The Transitional Metals Unit 38: Cells, Tissue, Organs and Organs systems
2. Slide 2: Science Interactive LTD Copyright 2005 Mitosis Meiosis Parent cell Parent cell DNA mixes DNA replicates & replicates Chromosomes 2 daughter cells separate 2 Daughter cells 4 daughter cells Unit 12  Mitosis and Meiosis 
3. Slide 3: Unit 12: Mitosis and Meiosis Science Interactive LTD Copyright 2005 Understand: Keywords: That lost or damaged cells need to replaced in 1. Inheritance, Genes, Chromosomes, Alleles, the human body by mitosis. Mitosis, Meiosis, Sperm, Ovum, Cells, Division, That mitosis is how organisms like humans grow 2. Clones, Reductive, Traits, Gametes, Variation, during pregnancy, through puberty to adult life. Characteristics, Recessive, Dominant, Genetic, That meiosis in humans leads to the production 3. Crosses, Diploid & Haploid. of the sperm and egg cells. That during meiosis, the number of 4. chromosomes in both the sperm and the egg cells are halved. That during meiosis, random crossing of 5. paternal and maternal DNA takes place producing genetically unique sperm and ovum. That this random crossing during meiosis leads 6. to variation in both the genotype and phenotype of humans. How the sex of an individual is determined by the 7. chromosomes we inherit from our parents. Click mouse to begin Science Interactive LTD PO BOX 50764 LONDON NW6 9AT web: www.science-interactive.co.uk email: sales@science-interactive.co.uk
4. Slide 4: Science Interactive LTD Copyright 2005 Numbers of cells Cells are the building blocks of all life. Unlike simple bacteria and other unicellular organisms, living organisms contain from many millions to billions of cells. Cells can have a very wide range of f___________ in the human body from skin cells, blood cells, muscle cells to nerve cells. Cells can only be viewed using a light microscope. Robert Hook was the first scientist to observe plant and animal cells using a simple light m___________ over 300 years ago. List the cell types that you have observed under a light microscope ? Numbers of cells in living organisms: Word bank: functions microscope Organism Bacteria Insect Small mammal Human Diagram Notes A bacteria is a simple A typical insect like a A small mammal, for A human contains many single celled organism. fly or a bee contains example a rat contains billions of cells. Each All the bacteria found many hundreds of many millions of cells hour of every day of our on the surface of this thousands of cells. organised into nine lives, we replace over planet weigh more than Insects have very basic distinct organ system one billion cells in our any other species. They organ systems that similar to our own. List body. During puberty we are very successful. support life and allow these organ systems ? produce even more cells. insects to reproduce.
5. Slide 5: Science Interactive LTD Copyright 2005 Essential cell organelles Cell organelles, like mitochondria and chloroplasts carry out important functions in plant and animal cells. The n_________ controls the activity of the cell by building new proteins including enzymes. It also contains DNA, the material of inheritance and is able to divide and produce new daughter cells during cell division or mitosis. Mitochondria found in both plant and animal cells respire glucose with o__________ releasing cellular e_________, carbon dioxide and water. Chloroplasts found only in plant cells produce glucose and oxygen from carbon dioxide and water ! Cell organelles in plants and animals: Word bank: nucleus oxygen energy Organelle Mitochondria Chloroplast Nucleus Cell membrane Diagram Mitochondria are found Found only in plant cells, The cell’s nucleus The cell membrane Function in both plant and animal chloroplast are able to contains the necessary controls the passage of cells. They respire combine carbon dioxide genetic information or substances in and out of glucose with oxygen to and water using the genes to produce new the cell. Movement of release energy for energy from light to cells, new enzymes and molecules happens by cellular activities. They produce glucose and new proteins. Humans passive diffusion or release CO2 and water. oxygen. have over 31,000 genes. active uptake.
6. Slide 6: Science Interactive LTD Copyright 2005 Specialised cells in animals Cells are designed for the specific function they play in the human body as part of the billions of cells that work to together to support life. A nerve cell for example is long and t_____ and conducts e__________ impulses. A red blood cell has a large surface area and no n________ so it can transport the maximum amount of oxygen from the lungs to the rest of the body. A muscle cells contains many more mitochondrial organelles than normal cells and are able to contract producing movement. How is a sperm specialised to perform its function ...List three things ? Specialised cells in animals: Word bank: thin electrical nucleus Cell Red blood cell Nerve cell Sperm cell Muscle cells Diagram Red blood cells contain Nerve cells form Sperm cells can propel Muscle cells contract Notes haemoglobin, have a connections with other themselves locating the providing movement. biconcave shape and no nerve cells, carry female egg cell prior to They are also rich in nucleus. They carry impulses along a huge fertilisation as well as mitochondria. This oxygen from the lung neural network that carrying paternal DNA. allows them to respire surface to the rest of the connect and coordinate They also have a glucose with oxygen body our actions and thoughts. streamlined head. producing energy.
7. Slide 7: Science Interactive LTD Copyright 2005 Specialised cells in plants As in animals, plant cells are also designed for the function they play as part of the millions of cells that work together to support life and produce food in green plants. A root hair cell, for example is long and extremely thin to aid the uptake of w_______ and dissolved minerals like nitrates and phosphates from the s______. The leaf palisade cell contains many chloroplast organelles which during photosynthesis produces glucose and o________ from carbon dioxide and water. Which other cells have large surface areas to aid absorption ? Specialised cells in plants: Word bank: water sun oxygen Cell Palisade cells Xylem cells Pollen cell Stomata cell Diagram Green leaves contain Water moves up the Pollen cells, the male Stomata cells found on Notes many palisade cells stem through the xylem gametes in plants are the underside of green which are rich in vessels. They are long normally transferred to leaves allows the chloroplasts that enable tubes reaching from the the female carpel by exchange of water, photosynthesis to occur. roots to the leaf tissue. insects. Pollen carries carbon dioxide and Why do root cells not Water moves in xylem the genetic information oxygen through the leaf have these cell parts ? cells by capillary action. to create a new plant. during photosynthesis.
8. Slide 8: Science Interactive LTD Copyright 2005 Cell size in plants and animals Cells in plants and animals vary in size. To visualize plant or animal cells we need to use a m___________. Animal cells on average, tend to be smaller and less regular in shape, when compared to plant cells. Both plant and animal cells grow and divide before becoming too large. Cells that are too large will have a reduced surface area to volume ratio. A small surface area to volume ratio reduces the amount of o__________ and nutrients that can be absorbed across its surface membrane. Cells must then divide or die. This is called mitosis. Cell size and mitosis: Word bank: microscope oxygen Cell Typical animal cells Typical plant cells Cell division in plants and animals Diagram Mitosis Parent cell Stage one 2n DNA replicates Stage two 4n Chromosomes 2n Stage three separate 2 Daughter cells Stage four 2n Photograph of human Photograph of plant As the cell volume increases, the ratio of surface Notes cheek cells. They are palisade cells. They are area to volume ratio deceases reducing the cells magnified 250 times. magnified 100 times. ability to allow sufficient nutrients and oxygen Use a ruler to measure Find their size using the across the cell membrane. Cells are able to divide their length. Now divide same method. Are they and clone themselves during mitosis. Over a by 250 to find their real smaller or larger than billion cells an hour are replaced in your body by cells dividing. size. human cheek cells ?
9. Slide 9: Science Interactive LTD Copyright 2005 Mitosis for replacing cells New cells are needed for you to grow and repair. These are made by cell divisions called mitosis. During mitosis, a cell d_________ and forms two identical clone cells. The human body produces up to one billion cells like this every hour replacing old worn out cells. New s______, muscle, blood, and nerve cells are all produced this way. Some species reproduce using mitosis. Bacteria, for example multiply using mitosis. What are the advantages of reproducing asexually ? Replacing cells by mitosis: Word bank: division skin Human Blood cells New skin cells Embryo growth Bacteria Diagram A human contains Blood cells last Skins cells are lost Embryo grow by Bacteria reproduce Notes many billions of only about 90 and replaced due to cloning cells. A multiply and spread cells. Each hour days before they normal wear and single zygote leads by cloning them- of every day, we need to be tear by mitosis. to the formation of selves. Each cell is replace over one replaced by the Every day we lose an embryo’s many identical to the billion cells in our marrow of the about 100 million millions of cells original bacterial body. long bones. skin cells. during pregnancy. cell.
10. Slide 10: Science Interactive LTD Copyright 2005 Mitosis Normal cell division Mitosis occurs during growth and repair. Mitosis leads to formation of new identical cells. Producing c______ or identical cells has several advantages. They behave just like the old ones and they don’t require anything but the original cell. What other advantages are there to producing identical clone cells ? Stages in mitosis: Word bank: clone Mitosis (normal cell division) Mitosis in plants Diagram Mitosis Parent cell Stage one 2n Stage two DNA replicates 4n Chromosomes Stage three 2n separate Stage four 2n 2 Daughter cells Notes Stage one: Chromosomes become visible and double inside the nucleus. The cell now contains 46 pairs of chromosomes. Stage two: The chromosomes move to the centre and line up before separation. Stage three: Each set of chromosomes separates moving to the cell poles before cell division. Stage four: The cell divides, producing two clone cells each containing 23 pairs of chromosomes. In the shoots and tips of plants new cells are formed during mitotic cell divisions. Each daughter cell is identical to the original cell. This picture shows several cells in various stages of mitosis.
11. Slide 11: Science Interactive LTD Copyright 2005 Meiosis gametes in humans Meiosis leads to the formation of only two types of cells. Meiosis in males forms the s______ and in females the o______ or egg cells. Meiosis halves the number of chromosomes, so that when the sperm and egg fuse, the fertilised zygote will have the correct number of chromosomes (23 chromosomal pairs). Meiosis also produces random gene mixing leading to variation of human traits in new individuals. Gamete production in the male and female: Word bank: sperm ovum Gametes Fertilisation Embryo Pregnancy sperm egg Gametes cells (sperm Sperm and egg cells are After fertilisation, all cells All of these 31,000 genes and egg) are produced haploid with only 23 of the developing embryo code for all the traits and by the testis and single chromosomes now contain 23 pairs of characteristics that make ovaries in the male only half the normal chromosomes with over human life unique. Cells and female. number 31,000 genes. now divide by mitosis.
12. Slide 12: Science Interactive LTD Copyright 2005 Meiosis Reductive cell division During meiosis, the number of chromosomes are halved so that the s______ and egg carries 23 single chromosomes. During meiosis, paternal genes that code for your characteristics randomly mix, so that we are all not the same. Name the cells in plants that are produces by the process of meiosis ? Stages in meiosis: Word bank: sperm Meiosis (reductive cell division) Sperm production Diagram Meiosis Stage one 2n Parent cell DNA mixes 4n Stage two & replicates 2 daughter cells Stage three 2n Stage four n 4 daughter cells Notes Stage 1: Chromosomes double and randomly mix inside the nucleus. The cell now contains 46 pairs of chromosomes. Stage 2: The chromosomes move to the centre and line up before separation. Stage 3: The cell divides, producing two new cells each containing 23 pairs of chromosomes. Stage 4: The two daughter cells divide again halving the number of chromosomes. Each gamete now contains only 23 single chromosomes. A sperm cell carries 23 single chromosomes and fuses with an egg cell which also carries 23 single chromosomes to form a zygote, which now carries the normal diploid number of chromosomes.
13. Slide 13: Science Interactive LTD Copyright 2005 Meiosis Determining sex by chromosomes Your chromosomes also determine what sex you are at b_______. In humans there are 23 pairs of chromosomes found in every cell. 22 pairs are identical, but pair 23 do not match. Pair 23 are called the sex chromosomes. All eggs from the female contain the X chromosome, sperm from the male contain either the X or Y chromosome. At f_____________, the egg may join with either an X or Y sperm producing equal numbers of males (XY) or females (XX). What are the gametes cells called in plants ? Inheritance of the sex chromosomes: Word bank: birth fertilisation Male Female Gamete cells Sex inheritance Egg Sperm XX Female XY Male Your sex is determined at the moment The gamete cells During fertilisation, the number of of fertilisation by the male sperm. An (sperm and egg) carry chromosomes are restored to their X carrying sperm produces a girl, and a only 23 single normal diploid number (23 pairs) The Y carrying sperm produces a boy. chromosomes. They embryo now grows by normal cell There is a 50: 50 chance of either sex. are haploid cells. division called mitosis.
14. Slide 14: Science Interactive LTD Copyright 2005 Meiosis gametes in plants Pollination is the transfer of pollen, the male sex cells from the a_________ of the stamen by b____ or insects to the surface of the female c_________. Once the pollen sex cells have landed on the female carpel, pollination has been achieved. Flowering plants contain both female and male reproductive organs and can either self or cross pollinate. Following fertilisation, where the ovule and pollen cell fuse, the seed begins to develop surrounded by the swollen ovule which forms the f_______. It is the function of the fruit to disperse the seed. What is this organ’s role in the plant life cycle ? Plant reproductive system: Word bank: anther bees carpel fruit Pollen cells Female carpel Male anther Reproductive system Diagram Pollen, the male sex The egg cells or ovules The stamen is the plant Flowering plants have Notes cells contain the contain the maternal male reproductive organ both male and female paternal genes and are genes and are held in the which contains many reproductive organs. held on the anther which ovule, part of the female millions of microscopic Plants can self or cross is part of the male carpel. pollen cells. pollinate. stamen.
15. Slide 15: Science Interactive LTD Copyright 2005 Meiosis Variation in humans one Humans have many of their genes which are common to us all. Over 99% of our genes in all the races are shared. Only 1% of human g_______ are unique and different. These genes code for differences in the colour of skin, eyes, hair and other features like the shape of our faces. Unless you’re an identical twin, your genes, your traits and you are unique amongst the other 5.5 billion human beings found on this planet. What are the advantages of variation in a species like humans ? Variation in humans: Word bank: genes Masai warrior Aborigine Arab Japanese Maori Diagram Notes Variation in humans (traits such as skin and eye colour) occur due to the random mixing of DNA during meiosis ensuring that no egg or sperm carry exactly the same genes or DNA and of course during fertilisation, when the genes from your mother and father mix to form you.
16. Slide 16: Science Interactive LTD Copyright 2005 Meiosis Variation in humans two Variation in the human race is caused by differences in your genes, caused by the random m______ of DNA during the production of sperm and egg and of course when the genes from your father and mother join during fertilisation. Your mother and father both share exactly 50% of your DNA and are your closest biological relatives. Brothers and sisters can share up to 50% of their DNA, but the figure is usually only around 25%. Why do brothers and sisters look very similar to one another ? Word bank: mixing Variation in humans: South American African Europe (North) Asian Europe (south) Diagram Notes Look around you in class, we all have certain similarities, but we are all unique. We belong to the same species, can reproduce with one another but are all different. Some people are taller or heavier or have different colour hair, skin or eyes. This is called variation. This is because we all have different genes in our cells from our parents.
17. Slide 17: Science Interactive LTD Copyright 2005 Extension questions and homework 1: Define the following terms: Chromosome, Gene, Allele, Characteristic, Diploid, Haploid, Trait, Genotype, Phenotype, Mutation, Recessive and Dominant. 2: Look at the three pictures below. Complete the table: Picture Mitosis/Meiosis Description Embryo growing during pregnancy Plant cells dividing at shoot tip Production of sperm and egg 3: Answer the following: a) Give 3 examples of human traits or characteristics b) Give 3 examples of traits or characteristics in plants. c) Name two cells that have a diploid number of chromosomes and two cells that have a haploid number of chromosomes. Do any cells in humans have no chromosomes. d) From the following, decide whether each cell is the result of mitotic or meiotic cell division. Blood cell Skin cell Sperm cell Plant ovum Pollen Muscle cell Sperm Bacteria
18. Slide 18: Science Interactive LTD Copyright 2005 4: The diagram below shows how the sex of a child is determined by the chromosomes inherited from both parents. (a) All human cells contain 46 chromosomes. How many chromosomes are there in Egg human egg or sperm cells. (b) Explain why either a daughter or a son will share some of the characteristics Sperm XX from both parents. Female (c) Explain why your parents are your closest living relatives. XY (d) What type of cell division leads to the formation of an embryo from a zygote Male during pregnancy. 5: Chromosomes occur in pairs in all cells except gametes. (a) What are alleles (b) Why are there two alleles for each characteristic. (c) Explain what is meant by dominant and recessive alleles. (d) The characteristics of humans are either inherited, or are caused by environmental influences. [Blood group, Weight, Eye-colour, Gender and Accidental loss of arm] (i) Which features are controlled by environmental influences (ii) Name one that is controlled by inheritance only (iii) One that is controlled by both. 6: A plant can either self or cross pollinate. Answer the following questions: (a) Which process (self or cross) leads to the production of (i) Identical offspring (ii) Different offspring. (b) List the advantages and disadvantages of asexual and sexual reproduction in plants. Internet: Go to google.co.uk and find about how cloning in plants is used by commercial growers to improve the quality and yield of a particular crop. Are there any disadvantages to cloning plants for commercial reasons.