2471335
Descripción
Fichas por Lauren Crawford, actualizado hace más de 1 año
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Creado por Lauren Crawford
hace más de 9 años
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| Pregunta | Respuesta |
| Most human and animal cells have which parts? | Nucleus Cytoplasm Cell membrane Mitochondria Ribosomes |
| What does the nucleus do? | Controls the activities of the cell |
| What is the cytoplasm? | Where most of the chemical reactions take place |
| What does the cell membrane do? | Controls the passage of substances in and out of the cell |
| What is the mitochondria? | Where most energy is released in respiration |
| What is a ribosome? | Where protein synthesis occurs |
| What do plant cells have that animal and human cells don't? | Cell wall made of cellulose Chloroplast Permanent vacuole |
| What does the cell wall do? | Strengthen the cell |
| What does the chloroplast do? | Absorb light energy to make food |
| Yeast is a ___________ organism | Yeast is a single-celled organism |
| What parts does yeast have? | Nucleus Cytoplasm Membrane Cell wall |
| What parts does a bacterial cell consist of? | Cytoplasm Membrane Cell wall (genes are not in a distinct nucleus) |
| Cells may be ______ to carry out a particular function | Cells may be specialised to carry out a particular function |
| By which process can dissolved substances move in and out of a cell? | Diffusion |
| What is the definition of diffusion? | The spreading out of particles from an area of high concentration to one of low concentration |
| The greater the difference in concentration, the _____ the rate of diffusion | The greater the difference in concentration, the faster the rate of diffusion |
| What does glandular tissue do? | Can produce substances such as enzymes and hormones |
| What does muscular tissue do in the stomach? | Churns the contents |
| What does glandular tissue do in the stomach? | Produces digestive juices |
| What does epithelial tissue do in the stomach? | Cover the inside and outside of the stomach |
| The digestive system includes: | Glands (e.g. pancreas/salivary) Stomach and small intestine Liver Small intestine Large intestine |
| What is the job of glands in the digestive system? | Produce digestive juices |
| Where does digestion occur? | In the stomach and small intestine |
| What occurs in the small intestine? | Absorption of soluble food |
| What happens in the large intestine? | Water is absorbed from the undigested food, producing faeces |
| Stems, roots and leaves are examples of what? | Plant organs |
| Examples of plant tissues | Epidermal tissues Mesophyll Xylem and phloem |
| What is the job of epidermal tissues? | They cover the plant |
| What does the mesophyll do? | Carries out photosynthesis |
| What do the xylem and phloem do? | Transport substances around the plant |
| What is the equation for photosynthesis? | Carbon dioxide + water -> glucose + oxygen (+ energy) |
| During photosynthesis, what absorbs light energy and where is it found? | It is absorbed by chlorophyll and it is found in chloroplasts |
| During photosynthesis, how is light energy used? | It is used by converting CO2 and water into sugar |
| During photosynthesis, oxygen is released as what? | Oxygen is a by-product of photosynthesis |
| What 3 factors can limit the rate of photosynthesis? | Shortage of light Low temperature Shortage of CO2 |
| In what 5 ways is the glucose, produced in photosynthesis, used? | 1. Stored as starch 2. Respiration 3. Producing fat or oil for storage 4. To produce cellulose 5. To produce proteins |
| What do plants absorb from the soil to help produce proteins? | They absorb nitrate ions |
| What 5 physical factors may affect the distribution organisms? | 1. Temperature 2. Availability of nutrients 3. Availability of light 4. Availability of water 5. Availability of oxygen and CO2 |
| Through what 2 methods can quantitative data on the distribution of organisms be obtained by? | 1. Random sampling with quadrats 2. Sampling along a transect |
| What are protein molecules made up of? | Long chains of amino acids |
| Proteins can act as 4 different things. What are they? | 1. Structural components of tissues e.g. muscles 2. Hormones 3. Antibodies 4. Catalysts |
| What do catalysts do? | Catalysts increase the rate of chemical reactions |
| What are biological catalysts? | Enzymes (enzymes are proteins) |
| What effect do high temperatures have on enzymes? | They change the shape of them; they become denatured |
| True or false. Different enzymes work best at the same pH levels | False. Different enzymes work best at different pH levels |
| Where is the enzyme amylase produced? | In the salivary glands, the pancreas and the small intestine |
| What does amylase do? | Amylase catalyses the breakdown of starch into sugars in the mouth and small intestine |
| Where is the enzyme protease produced? | In the stomach, the pancreas and small intestine |
| What does protease do? | Protease catalyses the breakdown of proteins into amino acids in the stomach and small intestine |
| Where is the enzyme lipase produced? | In the pancreas and small intestine |
| What does lipase do? | Lipase catalyses the breakdown of lipids into fatty acids and glycerol into the small intestine |
| What does the stomach produce and why? | Hydrochloric acid because the enzymes in the stomach work most effectively in the acidic conditions |
| What does the liver produce and where is the product stored? | The liver produces bile, which is stored in the gall bladder |
| Where is bile released into and what is its job? | It is released into the small intestine and it neutralises the acid that was added to food in the stomach |
| Why is it important to neutralise the acid that was added to the food in the stomach? | It provides alkaline conditions in which enzymes in the small intestine work most effectively |
| What are two uses of enzymes in the home? | 1. Bio detergents may contain protein-digesting and fat-digesting enzymes (proteases/lipases) 2. Bio detergents are more effective at low temps than any other type of detergent |
| What are 3 uses of enzymes in industry? | 1. Proteases to 'pre-digest' the protein in some baby foods 2. Carbohydrases to convert starch into sugar syrup 3. Isomerase to convert glucose syrup into fructose syrup, which is much sweeter so can be used in smaller quantities |
| Advantage of enzymes in industry | Enzymes work at normal temps and pressures that would otherwise require expensive, energy-demanding equipment |
| Disadvantages of enzymes in industry | Most enzymes are denatured at high temps and many are costly to produce |
| What are chemical reactions inside cells controlled by? | Chemical reactions inside cells are controlled by enzymes |
| What is the equation for aerobic respiration? | Glucose + oxygen -> carbon dioxide + water (+ energy) |
| Where do most of the reactions in aerobic respiration take place? | In the mitochondria |
| Energy that is released during respiration is used by the organism. In which 4 ways may the energy be used? | 1. To build larger molecules from smaller ones 2. In animals, to enable muscles to contract 3. In mammals and birds, to maintain a steady body temp in colder surroundings 4. In plants, to build up sugars, nitrates etc. into amino acids -> proteins |
| During exercise what two changes take place? | 1. The heart rate increases 2. The rate and depth of breathing increase |
| What do muscles store glucose as? | Glycogen which can then be converted back to glucose for use during exercise |
| During exercise, if insufficient oxygen is reaching the muscles, what does the body do? | The muscles use anaerobic respiration to obtain energy |
| What is anaerobic respiration? | The complete breakdown of glucose and produces lactic acid |
| Why is less energy released during anaerobic respiration than during aerobic respiration? | The breakdown of glucose is incomplete |
| Anaerobic respiration results in what? | Oxygen debt |
| What is a cause of muscle fatigue? | The build-up of lactic acid |
| What can remove lactic acid? | Blood flowing through the muscles |
| By what process do body cells divide? | Mitosis |
| What do chromosomes contain? | Genetic information |
| What two things happen when a body cell divides by mitosis? | 1. copies of the genetic material are made 2. the cell divides once to form two genetically identical body cells |
| Why does mitosis occur? | It occurs during growth or to produce replacement cells |
| How many sets of chromosomes do body cells have? | 2 sets of chromosomes |
| How many sets of chromosomes do sex cells (gametes) have? | One set of chromosomes |
| Cells in reproductive organs - testes and ovaries in humans - divide to form what? | Gametes |
| By what process do cells divide to form gametes? | Meiosis |
| What 2 things happen when a cell divides to form gametes? | 1. copies of genetic material are made 2. the cell divides twice to form 4 gametes each with a single set of chromosomes |
| What happens when gametes join at fertilisation? | A single body cell with new pairs of chromosomes is formed. An individual then develops by this cell repeatedly dividing by mitosis |
| What are stem cells? | Undifferentiated cells with the potential to form a wide variety of different cell types |
| Why does sexual reproduction give rise to variation? | When gametes fuse, one of each pair of alleles comes from each parent |
| What are the female sex chromosomes? | XX |
| What are the male sex chromosomes? | XY |
| What is an allele? | A version of a particular gene |
| What is a dominant allele? | The characteristic that will show up in the offspring even if only one of the alleles is inherited |
| What is a recessive allele? | The characteristic that will show up in the offspring only if both of the alleles are inherited |
| What are chromosomes made up of? | Large molecules of DNA which has a double helix structure |
| What is a gene? | A small section of DNA |
| Polydactyly is caused by which allele? | Dominant and can thus be passed on by only one parent you has the disorder |
| Cystic Fibrosis is caused by which allele? | The recessive and thus must be inherited from both parents. The parents must both be carriers |
| What evidence is there for early forms of life? | Fossils |
| What are fossils? | Fossils are the remains of organisms from many years ago, which are found in rocks |
| Name 4 ways fossils are formed? | 1. From hard parts of animals that don't decay easily 2. From parts that have not decayed because one or more conditions needed for decay are absent 3. parts of the organism that are replaced by other materials as they decay 4. As preserved traces of organisms |
| What 6 factors can cause extinction? | 1. environmental changes 2. New predators 3. New diseases 4. New, more successful predators 5. A single catastrophic event 6. through the cyclical nature of speciation |
| Why can uncertainty arise? (extinction) | A lack of enough valid and reliable evidence |
| As a result of what can new species arise? Make 4 points | 1. Isolation 2. Genetic variation 3. Natural selection 4. Speciation (interbreeding is no longer possible) |
| What is isolation? | Two populations of a species become separated |
| What is genetic variation? (extinction) | Each population has a wide range of alleles that control their characteristics |
| What is natural selection? | In each population, the alleles that control the characteristics which help the organism to survive are selected |
| What is speciation? | The populations become so different that successful interbreeding is no longer possible |
| Why would the number of bubbles produced/min be constant at 22-27 degrees C? | One factor is limiting e.g. carbon dioxide |
| 3 differences between aerobic and anaerobic respiration | aerobic uses oxygen lactic acid is the end result of anaerobic more energy from aerobic |
| Explain the advantage to someone of the change in heart rate during exercise (4 marks) | More oxygen is supplied to the muscles Faster removal of lactic acid More glucose to muscles Faster removal of CO2 |
| Stem cells can be used to treat a condition such as paralysis. Explain why | They can differentiate into nerve cells |
| Suggest one reason why many people think that stem cells should be obtained from umbilical cords instead of human embryos | Ethical issues with damage to embryo |
| Give two differences between mitosis and meiosis | Meiosis divides twice; mitosis only once. Cells produced by mitosis ave two sets of chromosomes, cells produced by meiosis have one set |
| Pros and Cons of embryo screening for Cystic Fibrosis | Pros - reduce no. of people with CF; reduce health care costs; allows decision Cons - possible damage to embryo; possible harm to mother; have to make ethical/ moral decision |
| Issues involved with embryo screening for polydactyly | Cures 'disfigurement' But condition isn't life threatening So risks unjustifed |
| Explain why only half the bars in a child's DNA fingerprint match the mother's fingerprint. | Eggs produced by meiosis The child only contains half its mother's chromosomes |
| Explain why scientists are uncertain about how life started on earth | Lack of valid evidence Because early organisms remains were destroyed by geological action |
| What is an organ? | Collection of tissues working together to perform a function |
| How do fossils provide evidence that species alive today have evolved from simpler organisms? | Fossil is remains of organism that lived a long time ago Fossils show changes over time Fossils have similar features to present day species |
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