4.7-4.9- Plant Cell Structure question and answers 2022/2023 correctly solved

4.7-4.9- Plant Cell Structure question and answers 2022/2023 correctly What are the three basic plant principles to build tall structure that are strong and flexible 1. they produce strong cell walls out of cellulose- a polymer made of sugar molecules 2. they build columns and tubes from specialised cells 3. they stiffen some of these special cells with another polymer called lignin Label a diagram of a plant cell Exam Question: What are the two fundamental differences between animal cells and plant cells 1. Plant cells have rigid cell walls, animal cells do not have cell walls 2. Plant cells contain chloroplasts, animal cells do not contain chloroplasts Describe the structure of a chloroplast Structure: a small flattened structure surrounded by a double membrane and also membranes inside called thylakoid membranes. These membranes are stacked up in some part of the chloroplast to form grana which are linked together by lamella- thin, flat pieces of thylakoid membrane What is the plural of granum? Grana What is the plural lamella? Lamellae What is the stroma? Thick fluid found in chloroplasts What is the function of the cytoplasm? Site of photosynthesis, energy from the Sun is used to make storage molecules, some parts of photosynthesis occur in the grana and other parts happen in the stroma Draw a diagram of a chloroplast Describe the structure of the amyloplast Structure: Storage vacuoles in the cytoplasm, enclosed by a membrane, small organelles Describe the function of the amyloplast Function: storage of amylopectin/starch grains in starch granules, also convert starch back to glucose for release when the plant requires it What is the tonoplast? The membrane around the vacuole (vacuolar membrane) Describe the structure of the vacuole? Vacuole Structure: A large central compartment surrounded by a vacuole membrane often found in plant cells Describe the function of the vacuole? Vacuole Function: Vacuole contains the cell sap which is made up of water, enzymes, minerals and waste products. Vacuoles keeps the cells turgid- stops the plants wilting. Also involved in the breakdown and isolation of unwanted chemicals in the cell. What is the function of the tonoplast? Tonoplast Function: Controls what enters and leaves the vacuole What are the parenchyma cells? A type of plant tissue found throughout the plant What is the function of the parenchyma cells? Cells fill spaces between more specialised tissues i.e. vascular bundles and may themselves have a specific specialised function. Also contribute to supporting leaves E.g. in roots they may have a role in storage and in leaves they contain chloroplasts and form photosynthetic tissue Describe the structure of the cell wall Structure: The outermost layer of the cell. Made of pectin/calcium pectate which holds plant cells together Describe the function of the cell wall Function: This layer acts as an adhesive- sticking adjacent plant cells together. Gives the plant stability Describe the structure of the plasmodesmata? Structure: Narrow fluid filled channels in the cell walls that link adjacent cells together by crossing the cells walls making the cytoplasm of one cells continuous with the cytoplasm of the next. Strands of cytoplasm connecting cells – cytoplasm is continuous between cells. Do cell walls completely separate plant cells? No- the plasmodesmata form channels What is the function of the plasmodesmata? Function: allow transport of substances and communication between cells Describe the structure of the pits? Structure: Regions of the cell wall where the wall is very thin because only the first layer of cellulose is deposited. They are arranged in pairs the pit in one cells is lined up with the pit in the adjacent cell. What is often found with a pit? Thinner areas of the cell wall where plasmodesmata are often found as well. What is the function of the pit? Function: Allow water movement between xylem vessels Exam Question: Amyloplasts and chloroplast come from the same type of unspecialised call. How do the two structures differ? · Amyloplasts are structures that store starch in plant cells · Chloroplasts have a complex structure of folded · Membranes that contain chlorphyll which traps the energy · From sunlight so plants can make its own food. Exam Question: Compare and contrast the structure of a typical plant cell with the structure of a typical animal cell. Typical plant and animal cells both have a nucleus, mitochondria, a cell surface membrane and cytoplasm. Animal cells may have temporary vacuoles, but a typical plant calls has a cells wall, permanent vacuole, sometimes chloroplasts and sometimes amyloplasts. Exam Question: Explain why chloroplasts are found only in particular parts of a plant. What do you think happens to make part of a plant e.g. potato tuber, turn green when exposed to light? Chloroplasts trap sunlight, so plant cells that don't receive enough light would be wasting energy is they made chloroplasts. If a potato Tuber, which is usually underground and so if white, is removed from the soil it starts to turn green. The cells on the surface of the potato must be able to make chloroplasts and the green pigment chlorophyll that is found in them What is the main energy storage molecule in plants, what do they use for energy? Cells get energy from glucose so starch supplies glucose and is the main energy storage molecule in plants Where in the plant does starch act as an energy storage molecule? Energy storage molecules especially in fruit, vegetables and cereals Where in the plant cell is excess glucose stored? Plants store excess glucose as insoluble starch in amyloplasts What is the advantage to having insoluble starch molecules? Doesn't cause water to enter cells by osmosis (would make them swell) this makes it a good storage molecule What does a plant do when it requires more energy? When a plant needs more glucose for energy it breaks down starch and this releases glucose Where is glucose seen in the human diet? Major source of energy in our diet, naturally: in fruit, vegetables, cereal. Used in making bread, pasta and other carbohydrate-rich food How is starch formed? Condensation reactions between alpha glucose monomers Describe the structure of starch Starch is a mixture of two polysaccharides: of alpha glucose: 1) Amylose: Long, unbranched chain of α glucose molecules, helical structure. Coiled structure, compact. 1,4, glycosidic bonds 2) Amylopectin: Branched chain of α glucose molecules. Side branches allow for rapid hydrolysis. 1,4, and 1,6 glycosidic bonds. Which glucose monomer is starch made of? Alpha glucose What sort of molecule is cellulose? A polysaccharide Where is cellulose found in plant cells? Major component of the plant cell walls: provides strength, forms thin cell wall How does cellulose help to improve the strength of the cell? Part of a plant's strength comes from the thin cellulose walls of the plant cells and the "glue" holding them together Is cellulose a long or short molecule? Long Is cellulose branched or unbranched? Unbranched Which isomer of glucose is cellulose made from? Beta- glucose How is cellulose important to humans, is it digestible? Important fibre in diet, indigestible by humans What are the two isomers of glucose? α glucose and ß glucose. What is the difference between the two isomers of glucose, draw a diagram of each to show this? 1. alpha glucose molecule has two hydroxyl groups adjacent to one another. 2. beta glucose the hydroxyl groups are on opposite sides of the molecule Why do the different isomers of glucose form different polymers? The different isomers form different bonds between neighbouring glucose molecules, and this affects the polymers they form Describe the formation of a cellulose molecule? A condensation reaction joins two β-glucose monomers together: Condensation reaction between the -OH group on the first carbon of one glucose and the -OH on the fourth carbon of the adjacent glucose links the two glucose molecules A 1,4- glycosidic bond forms What must happen to one of the glucose molecules in cellulose for a 1,6- glycosidic bond to form? Only possible if one of the molecules is rotated through 180 degrees- alternate (One glucose molecule must be inverted (flipped) so bonding can take place) Which bonds form in cellulose (and which do not), what properties does this give the molecule? In cellulose all the glycosidic bonds are 1,4 (no 1,6 glycosidic bonds as in starch) as the glycosidic bonds are straight so the cellulose chains are straight, so cellulose is a long unbranched chain molecule Are there any 1,4-glycosidic bonds in cellulose, why? No, 1,4 glycosidic bonds cannot be made because the two hydroxyl groups are not next to each other Is cellulose stronger if pulled in lengthways or widthways, why? Cellulose is stronger when pulled length ways rather than up/down across the microfibrils; because in this direction the stronger covalent bonds between the glucose units are being stretched, whereas in direction up/ down the weak hydrogen bonds are being stretched- takes less energy to break them making the molecule weaker. Draw a diagram of a cellulose chain, where are the side groups? Side groups are on alternative sides Give 9 similarities between cellulose and starch 1) Polysaccharides 2) Glucose 3) In plants 4) Contain 1,4 glycosidic bonds 5) Both contain hydrogen bonds 6) Insoluble 7) Formed by condensation reaction 8) Broken by hydrolysis 9) Both have each alternative glucose rotated through 180 degrees Give 9 differences between cellulose and starch 1) Starch is made of alpha-glucose 2) Cellulose is made of beta-glucose 3) Starch is made of two types of alpha glucose 4) Starch contain amylose and mylopectin compact spiral shape held in place by hydrogen bonds 5) In cellulose hydrogen bonds form between the -OH groups in neighbouring cellulose chains- forming bundles called microfibrils 6) Cellulose is made of one type of beta glucose 7) Starch also contains 1,6 glycosidic bonds 8) Starch is main energy storage material in plants 9) Cellulose forms microtubules which provide structural support How many glucose units are there in a cellulose chain? Each cellulose chain usually contains between 1000 and 10,000 glucose units Does cellulose wind into a spiral or remain as a straight chain? Remains as a straight chain (unlike amylose) What forms between the different cellulose molecules, what is this called? Hydrogen bonds form between the -OH groups in neighbouring cellulose chains called cross-linking- forming bundles called microfibrils Which groups do the hydrogen bonds form between? Hydrogen bonds form between δ+ hydrogen atoms and δ– oxygen atoms on OH groups that stick out from the cellulose molecules What are microfibrils made of? Bundles of 60 – 70 cellulose moleculessolved