Grade 8 Cell Structure and More.pptx

Cells Year 8 Biology Cells Cells are the basis of life Living organisms range from single celled organism (unicellular) to complex organisms (multicellular) Cell theory 1. All living things are composed of one or more cells 2. The cell is the smallest entity that retains the properties of life 3. Al...

Cells Year 8 Biology Cells Cells are the basis of life Living organisms range from single celled organism (unicellular) to complex organisms (multicellular) Cell theory 1. All living things are composed of one or more cells 2. The cell is the smallest entity that retains the properties of life 3. All cells come from pre-existing cells. Levels of organisation Complex organisms are made up of a number of different systems that work together. These systems are made up of organs. Each organ is made up of specific type of tissues These tissues are made up of cells Structure of cells Living things are classified into different kingdoms based on the characteristics of their cells. Plants and animals have specific types of cells with similarities and differences. Plant and animal cells contain membrane bound organelles, these are tiny structures that carry out specific functions within the cell. Plant cell structure Animal Cell Structure Task: Comparing cell structure Use the information on the previous two slides as well as the information on pages 48 49 of the textbook to draw a venn diagram which shows the similarities and differences in structure between plant and animal cells. Task Model Answer (no cheating) Task: Consolidation Answer questions 1 - 13 on page 53 of Science textbook. Specialised cells In multicellular organisms cells are specialised. That means, they have specific structures which enable them to perform specific functions. The human body contains over 200 different types of cells which work together to ensure all requirements of life are met. Examples of specialised cells in humans Read through the information on pages 58 – 59 in the textbook and explain the function of the following types of cells. Muscle cells - voluntary muscles – skeletal muscles - Involuntary muscles - Smooth muscles and Cardiac muscles Nerve cells Blood cells Fat cells Animal Tissues Complex animals consist of four basic tissue types Connective Tissue Function - Support - Binds other tissues together - Protects against damage, infection and heat loss Examples: Fat, bone, cartilage, ligaments and tendons Epithelial Tissue Function - Line internal and external surfaces, such as blood vessels, digestive organs, kidney tubules, skin and air ways. - Act as a barrier, protecting against mechanical injury, pathogens and fluid loss. - Some are specialised to function in absorbsion, secretion or excretion. Nervous Tissue Function - Provides the means of communication between all body structures Key structural feature - Highly specialised features of neurons enable them to effectively pass messages between the nervous system to other parts of the body. Muscle Tissue Function Can contract when stimulated by nerve impulses. Key structural feature Made of long and thin thread like cells called muscle fibres. Task: Consolidation Use the information on pages 65 – 68 to answer questions 1 - 15 on page 71 of Science textbook.