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Description
Flashcards by Ben Tomsett, updated more than 1 year ago
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Created by Ben Tomsett
over 7 years ago
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| Question | Answer |
| What is the difference between prokaryotes and eukaryotes? | Eukaryotic cells are complex, which include animal and plant cells. Prokaryotic cells are smaller and simpler (i.e. bacteria) |
| What are all living things made out of? | Cells |
| Name the 5 main subcellular structures in an animal cell, and state what they do. | Nucleus - contains genetic material that controls the activities of the cell Cytoplasm - substance in which most chemical reactions happen, helped by enzymes Cell membrane - holds the cell together and controls what goes in and out Mitochondria - where most reactions for aerobic respiration take place Ribosomes - where proteins are made for the cell out of amino acids |
| Name the 3 plant-exclusive subcellular structures in a plant cell and state what they do. | Cell wall - cellulose wall that strengthens the cell Permanent vacuole - contains cell sap, a weak solution of sugar and salts Chloroplasts - where photosynthesis occurs, which uses a green substance called chlorophyll to absorb light and make energy for the plant |
| What type of organism are bacteria? | A prokaryote (or single-celled organism) |
| What is the formula for magnification? | magnification = image size / real size |
| What is the process by which cells change to become specialised? | Differentiation |
| How is a root hair cell specialised for it's function? | It has a large surface area, allowing it to absorb water and mineral ions from the soil |
| How does the structure of the sperm cell help it perform its function? | Its long tail lets it 'swim' through the uterus, and the many mitochondria in the cell provide it with the energy needed. the enzymes in the top of its head help it digest through the cell membrane |
| What part of the cell contains genetic material? | The nucleus |
| What is the name given to coiled up length of DNA molecules in a double helix shape? | Chromosomes |
| How many pairs of chromosomes does a human cell have? | 23 |
| What are the two phases of cell division? | Interphase and the mitotic phase |
| Describe what happens in the interphase. | The cell grows physically larger, duplicates organelles (namely ribosomes and mitochondria). Then, it synthesises a complete copy of the DNA, and grows more and organises its contents ready for mitosis. |
| Describe what happens during mitosis. | The chromosomes line up at the centre of the cell, and fibres pull them apart. The two arms of each chromosome go to the opposite ends of the cell. Membranes form around each set of chromosomes, which form the nuclei of the new cells. Lastly, the cytoplasm and cell membrane divide. |
| What are the two new cells produced after mitosis called? | Daughter cells |
| How do prokaryotic cells replicate? | Binary fission |
| Describe what happens during binary fission. | The circular DNA and plasmids replicate, and the cell gets bigger. The circular DNS strands move to opposite poles of the cell, cytoplasm begins to divide, and new cell walls begin to form. The cytoplasm eventually divides and two daughter cells are produced. |
| What are the best conditions for cells to replicate? | Warm environments with lots of nutrients. |
| How do you calculate the number of bacteria in a population? | Put the given time into minutes, and divide by the mean division time. Then, find the value of 2 to the power of the result. |
| Where can stem cells be found? | Human embryos, the umbilical cord, and bone marrow. |
| Name some reasons people are against embryonic stem cell research. | -- Each embryo could potentially be a human life -- |
| Which part of the plant is where growth occurs? | The meristem |
| What is one useful purpose of using meristems to produce identical plants? | To prevent rare species being wiped out, or to reproduce plants that have features desirable to farmers |
| What is diffusion? | The movement of particles from an area of high concentration to an area of lower concentration, down a concentration gradient |
| Where does diffusion happen? | Diffusion happens in solutions and gases |
| What is a concentration gradient? | The concentration gradient is the difference in concentration of a dissolved substance between a region of high to low concentration |
| What factors increase the rate of diffusion? | *Higher temperatures *Higher concentration gradients *Heavier molecules diffuse slower * Diffusion distance |
| Can molecules diffuse across a cell membrane? | Yes, small molecules such as oxygen, glucose, amino acids, and water can diffuse through a cell membrane |
| When does diffusion stop? | When all molecules in the solution/gas have reached equilibrium (are evenly spread out) |
| What is osmosis? | Osmosis is the diffusion of water molecules across a partially permeable membrane |
| Which direction do these water molecules travel across the membrane? | Both ways |
| What is active transport? | Active transport is the movement of molecules across a concentration gradient, but the wrong way -- molecules move from an area of low concentration to an area of high concentration |
| What does active transport need? | Energy, in the form of protein (specifically ATP - Adenosine triphosphate) |
| Where do some examples of active transport happen? | * Root hair cells on the root of plants use active transport to absorb nutrients * In the gut, glucose, amino acids and other nutrients are absorbed into the blood using active transport |
| How do you calculate surface area and volume, and put them into a ratio? | Surface area: WIDTH x HEIGHT Volume: WIDTH x HEIGHT x DEPTH Put it into a ratio: SURFACE AREA:VOLUME |
| When does differentiation occur? | During the development of a multicellular organism (conception to birth) |
| What are groups of similar cells known as? | Tissues |
| Name three cell tissues | * Muscular tissue * Glandular tissue * Epithelial tissue * Nervous tissue |
| What are tissues organised into? Name some | Organs: * Stomach * Brain * Intestines * Liver * Kidneys |
| What are organs organised into? Name some | Organ systems: * Glands * Intestinal system * Circulatory system * Nervous system |
| What controls chemical reactions in an organism? | Enzymes |
| What is a catalyst? | A substance which increases the speed of a reaction without being changed or used up in the reaction. |
| What are enzymes made out of? | Large proteins (chains of amino acids) |
| What is an active site? | The area of an enzyme where the substrate fits into it and speeds up a reaction. The active site is complementary to the shape of the enzyme. |
| How are enzymes denatured? | * By heating them to more than 40 degrees Celsius * By raising the pH to a lot above or below 7 (neutral) |
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