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N5- Unit 2 MO1-Cells, tissues, organs, stem cells and meristems 1.Describe specialisation in cells A process whereby cells have changed their shape or metabolism to carry out a particular function (i.e. job). 2.Summary of the body Specialised cells tissues organs systems organisation 3. What is a tissue? A group of cells of the same type. 4. What is an organ? Different tissues working together to do a job. 5. Examples of systems Circulatory, respiratory, reproductive etc… 6. For the following cells, state the type of cell, its function and adaptations Type of cell: Root hair cell Function: Absorbs water and mineral from the soil Adaptations: Long 'finger-like' extension with very thin wall, which gives a large surface area. Type of cell: Palisade cell Function: Site of photosynthesis Adaptations: Contains lots of chloroplasts Type of cell: Sperm cell Function: reproduction/ fertilization of the egg Adaptations: has a tail to swim and many mitochondria to release energy. Type of cell: Egg cell Function: Reproduction/being fertilized by the sperm cell. Adaptations: large cell containing food reserves. Type of cell: Red blood cell Function: carry oxygen Adaptations: contains haemoglobin to carry oxygen, large surface area to allow diffusion, flexible to go through capillaries. 7.What are stem cells? 8. What can happen to a stem cell went it divides? 9. What are stems cells needed for? 10. Give examples of the use of stem cells in medicine 11. What are meristems? 12. What are the two types of meristems, where are they found, what is their job? 13. Give 3 examples of plant tissues formed after cells specialise. Cells which give rise to specialised cells. It can either produce more stem cells or produce a different type of cell. Growth and repair. - treat burns - diabetes The region of a plant where cells divide. Apical meristems: in buds and at the tip of roots. They are responsible for growth in length. Lateral meristems: inside shoots and roots of woody plants, forming a ring. They are responsible for growth in girth. - Xylem - Phloem - Epidermis N5- Unit 2 M03- Control – Nerve and hormones 1-Why is internal communication For survival of multicellular organisms because cells in needed? multicellular organisms do not work independently. Nervous control 2- What is the nervous system The central nervous system (CNS, made of the brain made of? and the spinal cord.) and the nerves. 3- Identify the parts of the brain 1- Cerebrum: the largest part, divided into two halves. and their function Different regions are responsible for memory, conscious thought, reasoning, intelligence, personality. 2- Cerebellum: controls balance and co-ordination. 3- Medulla: controls automatic functions of the body: breathing, heart beat, etc… 4- What is a stimulus? Other name for it? 5- Job of the sensory neuron and consequence? 6- Job of the motor neuron? 7- What is a relay/intermediate neuron? 8- In what form is the message carried along a neuron? 9- What is the name of the gap found between 2 neurons? 10- How is the message passed from on neuron to the next? 11- What is a reflex action? 12- Describe examples of reflex actions. 13- Describe how a reflex action works, using the simple model of a reflex arc. A change in conditions that is detected by a receptor. Other name: sensory input. To pass the message to the CNS. The CNS processes the information from our senses which needs a response Motor neurons enable a response brought about by the CNS to occur. It can be a rapid action from a muscle or a slower response from a gland. A nerve cell which is found between a sensory and a motor neuron. The relay neuron is part of the CNS (i.e. brain and spinal cord). Electrical impulses carry messages along neurons. A synapse. Chemicals transfer these messages across synapses. It is a fast automatic responses which require no input from the brain. Reflex actions either protect the body from damage (e.g. removing hand from heat, pupil of the eye becoming smaller in bright light to protect the sensitive cells at the back of the eye from damage, sneeze) or help its normal functioning (e.g. swallowing). It is the passage of an impulse from a sensory neuron, across a relay neuron to a motor neuron. Receptors (1) are stimulated (e.g. pain) and send a nerve impulse though the sensory neuron (2). From the sensory neuron, the message has to pass through a synapse (junction, 3) before it reaches the intermediate neuron or relay neuron (4) in the spinal cord. From the intermediate/relay neuron, it crosses another synapse (5) and travels down a motor neuron (6) which stimulates a muscle to contract (7) (e.g. jerking movement of the hand). Hormonal control 14-Features of hormones 15- What releases hormones directly into the blood stream and why? 16- How are hormones perceived by the target tissue? 17- Why are hormones ignored by non-target tissues? 18- Which organ detects changes in blood glucose level? 19- How and where is glucose stored in the body? 20- Explain the role of insulin in the control of blood glucose levels. 21- Explain the role of glucagon in the control of blood glucose levels. 22- What can happen if blood glucose levels are not controlled? (2 answers) 23- What is diabetes? 24- Consequences of diabetes 25- Treatment of diabetes 26- Give two reasons for the recent increase in the number of people with diabetes in Scotland - Chemical messengers - Made of protein - Carried in the blood Endocrine glands release hormones in the blood stream so that they can travel to target tissues. Cells have receptors on their surface. Because non-target tissues don’t have receptors for them. The pancreas. As glycogen (many glucose molecules chemically bound) in the liver. When blood glucose level increases, the pancreas releases more insulin, which travels to the liver where it activates enzymes in the liver cells to convert glucose into glycogen. When the blood glucose level decreases, the pancreas releases more glucagon, which travels to the liver where it activates enzymes in the liver cells to convert glycogen into glucose. - it is important to control blood glucose levels since, if they are high, they can cause damage to blood vessels and affect the functioning of the eyes and kidneys in particular. - uncontrolled blood glucose levels can cause problems with osmosis in cells. A communication pathway that has failed due to a fault in release or a failure to respond to insulin High blood glucose levels (see above n.22) Injections of insulin to help the uptake of glucose from the blood to the cells. - Poor diet - Lack of exercise N5- Unit 1 MO4- Variation and Inheritance 1- Variation 1- What is the cause of the observed variation within species? 2- What is discrete variation? Examples Type of inheritance 3- What is continuous variation? Examples Type of inheritance 4- What is the most common type inheritance and variation? 2- The genetics of inheritance 1- State what genes are. 2-State what controls a characteristic (e.g. type of ear lobe, blood group, height) 3- State the name given to the different forms of a gene 4-State the meaning of homozygote (1) and heterozygote (2). 5- Explain what is meant by phenotype. Identify examples of phenotypes of the same characteristic. 6- Explain what is meant by dominant and recessive alleles The combination of genes from two parents. Changes in values for a characteristic which are clear-cut and fall into separate categories. E.g. blood group, type of ear lobe (freeattached), ability to roll tongue, pea flower colour, pea colour. Single gene inheritance (controlled by 1 gene only). Changes in values for a characteristic over a range, between a minimum and a maximum. E.g. human: height, foot size Plants: height, tree girth Polygenic inheritance (controlled by more than 1 gene). Polygenic inheritance and continuous variation. Genes are parts of chromosomes Inherited characteristics are controlled by the two forms of a gene. Alleles (1) Organism with 2 identical alleles for one gene (2) Organism with 2 different alleles for one gene Phenotype: the external expression of a feature controlled by one or more genes. Examples of phenotypes for the same characteristic: Hair colour: blond, brown Ability to roll tongue: roller, non-roller Seed shape: round, wrinkled Dominant: allele which shows up in the phenotype. Recessive: allele which phenotype is hidden when present alongside a dominant allele. 7- Explain what is meant by genotype. How is it represented? 8- Identify using letters the successive generations of a cross. 9- For a cross between two homozygotes parents of different phenotype. - State what is the phenotype of the first generation - Predict the proportion of the phenotypes of the second generation 10- Explain differences between observed and predicted figures in monohybrid crosses. 11- In family trees, by which individual should you start to work out genotypes? - Combination of genes in a gene pair - Genotype is represented by 2 letters (one letter for each allele). Dominant alleles are shown as capital letters, recessive alleles are shown in small caps. Parents: P First generation: F1 (First filial) Second generation: F2 (Second filial) All F1 organisms have the same phenotype; They are said to be uniform. A ratio of 3:1 3 showing dominant phenotype. 1 showing recessive phenotype. - random nature of fertilisation - death of embryo – death of seedlings Individuals with the phenotype of the recessive allele. MO5- Plant transport 1- Explain the need for a transport system in plants. 2- Which parts of the plant are involved in water transport? 3-Why is water needed by the plant? 4- Describe the uptake of water from soil by plant roots and the role of the root hair cells in this process 4- Describe the role of the xylem 5- Characteristics of the xylem - to transport water and minerals from roots to leaves where photosynthesis takes place - to transport food (i.e. sugar) from leaves to parts of the plant which do not make food - root hairs. - xylem vessels. - to transport minerals - for photosynthesis Water moves into roots by osmosis from the area of high water concentration in the soil to the area of low water concentration in cells. Root hair cells increase the surface area of root for osmosis. Transport water and soluble minerals after they enter root hairs to all parts of the plant up to leaves where it is needed for photosynthesis. - made of dead vessels - strengthened by lignin rings 6- Explain why the strengthening of the xylem is needed? Xylem cells are lignified to withstand the pressure changes as water moves through the plant. 7- Describe the role of the phloem Sugar is transported up and down the plant in living phloem, food from food-producing cells to other parts of the plants where it is needed (root, shoots and fruits). 8- Identify xylem and phloem from the diagrams: - 1: xylem (at the centre of the root and stem’s vascular bundle; on the upper side of the leaf’s vein) - 2: phloem (to the outside of the vascular bundle in the root and stem; on the lower side of the leaf’s vein) 9- Describe the structure of the xylem and identify other functions of the transport system. 1- cell wall 2- ring of lignin 3- pit ( allow water and minerals to reach neighbouring cells 4- direction of the flow (from roots to leaves) 5- xylem tube 10- Describe the structure and function of cells in the phloem. Identify the different parts from a diagram. - Phloem is made of two types of living cells: - sieve tubes: cells arranged as a tube with perforated cell wall in between (sieve plate). Strands of cytoplasm transport sugar from cells to cells. - companion cells: have nucleus and cytoplasm, they control neighbouring sieve tubes. 12345- 12- State how gases go in and out of leaves. 13- State which gases go out and which go in through these holes 14- Describe the external features and internal structures of a leaf in relation to its function in gas exchange. sieve tube sieve plate strands of cytoplasm companion cell direction of flow, from photosynthesising cells in leaves to cells that cannot produce their own food. Through holes called stomata which are found mostly on the lower surface of leaves. - CO2 (in for photosynthesis, out from respiration) - O2 (mostly out from photosynthesis, in for respiration at night) - Water vapour (out whenever stomata are opened) 1- Waxy cuticle: prevents water loss 2- Upper epidermis: protection 3- Palisade mesophyll: where most photosynthesis takes place. 4- Spongy mesophyll: where some photosynthesis takes place. Cells are not compactly packed and have a large surface area exposed to air. This allows the diffusion of carbon dioxide into cells. 5- Air spaces: allow free movement of gases inside the leaf. 6- Lower epidermis: protection 7- Guard cells: specialist cells which open or close the stoma 8- Stoma 9- Phloem 10- Xylem 11- Veins: hold xylem and phloem 15- Which type of leaf cell requires water for photosynthesis? 16- What is transpiration? Palisade and mesophyll cells 17- What is the process responsible for water loss when the stomata are opened? 18- What environmental conditions would produce the greatest transpiration rate? 19- Summarise the path of water through the plant Evaporation Transpiration is the loss of water through leaves. Warm and windy. 1-Enters root hair by osmosis 2-travels in stem by xylem. 3-leaves the mesophyll cell by evaporation. 4exit the plant by transpiration through stoma MO6/7/8- Transport in animals Blood 1-In mammals, what is transported in the blood? 2- What is the function of red blood cells? 3-How are red blood cells adapted to their function? 4-Explain the function of haemoglobin in the transport of oxygen The lungs Explain the function of mucus, cilia and cartilage in the trachea and bronchi Describe the internal structure of the lungs. (name and role in breathing) Larynx 1 2 3 3 4 Nutrients, oxygen and carbon dioxide To transport oxygen around the body - biconcave in shape: increase surface area for diffusion of oxygen - no nucleus: more space for oxygen - contain haemoglobin: a pigment which allows them to transport oxygen efficiently in the form of oxyhaemoglobin To transport oxygen In lungs: Haemoglobin binds oxygen to become oxyhaemoglobin In tissues: Oxyhaemoglobin separates into haemoglobin and oxygen for cells to use. Mucus: traps dirt and micro-organisms. Cilia in the trachea: push mucus upwards and away from the lungs towards the throat and the oesophagus. Once in the stomach, germs are destroyed by stomach acids. Cartilage in the trachea and bronchi: keep main airways open. 1- Trachea: the air passes through the larynx and through the trachea (1). 2- Bronchus (plu. bronchi): after the trachea, the air flow is divided within the 2 bronchi which connect to each lung. 3- Bronchioles: bronchi which have divided many times and are smaller in size. 4- Alveoli: air sacs. 5- Blood capillaries surrounding the alveoli 5 Where does gas exchange take place? In the alveoli What features of the alveoli are important for its function? For a more efficient diffusion of gases: alveoli have a large surface area, thin walls and a good blood supply. Describe the path of oxygen in the alveoli From cell of the alveoli wall to cells of the capillary wall to plasma to blood cells. Explain why the oxygen moves along that pathway? The heart 8- Identify the four chambers of the heart It diffuses from an area of high concentration to an area of low concentration. 1 1- Right atrium (Plural atria) 2- Right ventricle 3- Left atrium (Plural atria) 4- Left ventricle 3 2 2 4 9- Describe the path of blood flow through the heart and blood vessels connected to it. 6 8 4 5 3 1 7 3 2 4 Describe the positions and functions of the heart valves. V2 2 V1 Function of Coronary artery Blood return from organs via the vena cava (5) and enters the right atrium (1). When the right atrium is full, the blood is squeezed into the right ventricle (2). The muscular wall of the right ventricle contracts and pushes the blood through to the pulmonary artery (6) towards the lungs. Blood return from the lungs via the pulmonary vein (7) and enters the left atrium (3). When the left atrium is full, the blood is squeezed into the left ventricle (4). The muscular wall of the left ventricle contracts and pushes the blood through to the aorta (8). When the atria are full, the blood is squeezed into the ventricle and valves (V1) prevent its return to the atria. When the ventricles are full, the blood is squeezed towards the arteries (pulmonary artery and aorta) and valves (V) prevent its return to the ventricles. To bring blood to the heart muscle. Blood vessels Describe the structure of the arteries Describe the function of the arteries Describe the structure of the veins Describe the function of the veins Describe the structure of the capillaries Describe the function of the capillaries Arteries have thick, muscular walls, a narrow central channel Arteries carry blood under high pressure away from the heart. They have thinner walls and a wide channel. Veins contain valves to prevent backflow of blood and carry blood towards the heart. Veins carry blood under low pressure Capillaries form networks at organs and tissues, are thin walled and have a large surface area. They allow exchange of materials between the blood and cells. Intestines How is food moved in the digestive system. By peristalsis: a wave of muscular contraction in the wall of the digestive tract: muscles behind the food contract and the muscles in front relax. Explain how the structure of the small intestine is related to its function. - it is very long - covered in finger-like villi area - has folds - very thin lining of cells of - rich blood supply Explain how the structure of a villus is related to the absorption and transport of food. increases surface Fast transport nutrient to blood - structure of villus: allows efficient absorption of digestion products - (1) one cell thick layer allows fast transport of nutrient - (2) blood capillaries: carry away glucose and amino-acids - (3) lymphatic vessels (lacteal): absorb fatty acids and glycerol (the products of fat digestion).