Hard Stuff Flashcards
What parts do animal cells have?
- Nucleus.
- Cytoplasm.
- Cell Membrane.
- Mitochondria.
- Ribosomes.
What parts do plant cells have?
- Nucleus.
- Cytoplasm.
- Cell membrane.
- Mitochondria.
- Ribosomes.
- Rigid cell wall.
- Permanent vacuole.
- Chloroplasts.
What does the nucleus do in a cell?
-Contains genetic material that controls the activities of the cell.
What does the Cytoplasm do in the cell?
-Gel-like substance where most of the chemical reactions happen. It contains enzymes that control these chemical reactions.
What does the Cell membrane do in the cell?
-Holds the cell together and controls what goes in and out.
What do the Mitochondria do in the cell?
-These are where most of the reactions for respiration take place. Respiration releases energy that the cell needs to work.
What do Ribosomes do in the cell?
-These are where proteins are made in the cell.
What does the rigid cell wall do in the cell?
-Made of cellulose. It supports the cell and strengthens it.
What does the permanent vacuole do in the cell?
-Contains cell sap, a weak solution of sugar and salts.
What do chloroplasts do in the cell?
-These are where photosynthesis occurs, which makes food for the plant. They contain a green substance called chlorophyll.
What is yeast and what does it contain in its cell?
- Yeast is a single-called microorganism.
- It has a nucleus, cytoplasm, and a cell membrane surrounded by a cell wall.
What is Bacteria and what does its cell contain?
- Bacteria is a single-celled microorganism.
- A Bacteria has a cytoplasm and a cell membrane surrounded by a cell wall.
- The genetic material floats in the cytoplasm because bacterial cells don’t have a nucleus.
What is the definition for diffusion?
-Diffusion is the spreading out of particles from an are of high concentration ton an area of low concentration.
What states does diffusion happen in?
-Solutions and gases - that’s because the particles in these substances are free to move about randomly.
What happens to the rate of diffusion when the the difference in concentration increases?
-The bigger the difference in concentration, the faster the diffusion rate.
How do dissolved substances move in and out of cells?
-Dissolved substances can move in and out of cells by diffusion.
How do cell membranes help diffusion?
- Only very small molecules can diffuse through cell membranes - things like oxygen (needed for respiration) glucose, amino acids and water.
- Big molecules like starch and proteins can’t fit through the membrane.
Which way do particles flow in diffusion?
-They’re only moving about randomly, so they go both ways - but if there are a lot more particles on o e side of the membrane, there’s a net (overall) movement from that side.
How are Palisade Leaf Cells adapted for Photosynthesis? (4 points).
- Packed with chloroplasts for photosynthesis. More of them are crammed at the top of the cell - so they’re nearer the light.
- Tall shape means a lot of surface area exposed down the side for absorbing CO2 from the air in the leaf.
- Thin shape means that you can pack loads of them in at the top of a leaf.
- Palisade leaf cells are grouped together at the the top of the leaf where most of the photosynthesis happens.
What are Guard Cells adapted to doing?
-Opening and Closing Pores.
What are Palisade Leaf Cells adapted to doing?
-Photosynthesis.
How are Guard Cells adapted to allowing gas exchange and controlling water loss within a leaf? (5 points).
- Special kidney shape which opens and closes the stomata (pores) in a leaf.
- When plants have lots of water, guard cells fill up with it - go plump and turgid. Makes stomata open so gases can be exchanged for photosynthesis.
- When plant is short of water, guard cells lose water - become flaccid, making stomata close. Helps stop too much water vapour escaping.
- Thin outer walls and thickened inner walls make opening and closing work.
- Also sensitive to light and close at night to save water without losing out on photosynthesis.
What are Red Blood Cells adapted to do?
-Carry oxygen.
How are red blood cells adapted to carry oxygen? (4 points).
- Concave shape gives a big surface area for absorbing oxygen. Also helps them pass smoothly through capillaries to reach body cells.
- Packed with haemoglobin - the pigment that absorbs oxygen.
- Have no nucleus, to leave even more room for haemoglobin.
- Red blood cells = an important part of the cell.
What are sperm and egg cells specialised to do?
-Reproduction.
How are egg cells adapted for reproduction? (4 points).
- The main functions of an egg cell are to carry the female DNA and to nourish the developing embryo in the early stages.
- The egg cell contains huge food reserves to feed the embryo.
- When a sperm fuses with the egg, the egg’s membrane instantly changes its structure to stop any more sperm getting in. This makes sure the offspring end up with the right amount of DNA.
- Sperm and egg cells are very important cells in reproduction.
How are sperm cells adapted for reproduction? (6 points).
- The function of a sperm is basically to get the male DNA to the female DNA.
- It has a long tail to help it swim to the egg.
- It has a streamlined head to help it swim to the egg.
- There are a lot of mitochondria in the cell to provide the energy needed.
- Sperm also carry enzymes in their heads to digest the egg cell membrane.
- Sperm and egg cells are very important cells in reproduction.
How do cells become specialised for a particular job?
-Differentiation.
When does differentiation occur?
-Differentiation occurs during the development of a multicellular organism.
What are similar cells organised into?
-Similar cells are organised into tissues. A tissue is a group of cells that work together to carry out a particular function.
What are three examples of tissues and what they do?
- Muscular tissue, which contracts (shortens) to move whatever it’s attached to.
- Glandular tissue, which makes and secretes chemicals like enzymes and hormones.
- Epithelial tissue, which covers some parts of the body, e.g. the inside of the gut.
What are tissues organised into?
-Tissues are organised into Organs. An organ is a group of different tissues that work together to perform a certain function.
What are examples of tissues that the stomach (organ) is made up of?
- Muscular tissue, which moves the stomach wall to churn up the food.
- Glandular tissue, which makes the digestive juices to digest food.
- Epithelial tissue, which covers the outside and the inside of the stomach.
What are the organs organised into?
-Organs are organised into Organ Systems. An organ system is a group of organs working together to perform a particular function.
What organs are in the digestive system (found in humans and mammals) which breaks down food?
- Glands (e.g. the pancreas and salivary glands) which produce digestive juices.
- The stomach and small intestine, which digest food.
- The liver, which produces bile.
- The small intestine, which absorbs soluble food molecules.
- The large intestine, which absorbs water from undigested food, leaving faeces.
What organs are plants made up of?
- Stems.
- Roots.
- Leaves.
What tissues are leaves made up of and what do they do?
- Mesophyll tissue - this is where most of the photosynthesis in a plant occurs.
- Xylem and phloem - they transport things like water, mineral ions and sucrose around the plant.
- Epidermal tissue - this covers the whole plant.
What is the equation for photosynthesis?
-Carbon dioxide + water >(sunlight and chlorophyll.)> glucose + oxygen.
What does photosynthesis produce?
- Glucose - ‘food’.
- Oxygen.
Where does photosynthesis occur in a plant cell?
-Photosynthesis happens inside the chloroplasts.
How does photosynthesis occur in the chloroplasts?
-Chloroplasts contain a green substance called chlorophyll, which absorbs sunlight and uses its energy to convert carbon dioxide (from the air) and water (from the soil) into glucose. Oxygen is produced as a by-product.
What type of plants does photosynthesis occur in?
-Photosynthesis happens in the leaves of all green plants - this is largely what the leaves are for.
What factors can become the limiting factor in the rate of photosynthesis?
- Light.
- Temperature.
- CO2.
What are some examples of the environmental conditions affecting which factor is the limiting factor?
- At night light is the limiting factor.
- In winter it’s often the temperature that is the limiting factor.
- If it’s warm enough and bright enough, the amount of CO2 is usually the limiting factor.
What is an easy experiment to work out the ideal conditions for photosynthesis in a particular plant?
- Easiest type is to use a water plant like Canadian pondweed - you can easily measure the amount of oxygen produced in a given time to show how fast photosynthesis (oxygen is produced in photosynthesis).
- You could either count the bubbles given off, or if you want to be a bit more accurate you could collect the oxygen in a gas syringe.
How does light affect the rate of photosynthesis?
-Light provides the energy needed for photosynthesis.
-As the light level is raised, the rate of photosynthesis increases steadily - but only up to a certain point.
-Beyond that, it won’t make any difference because then it’ll be either the temperature or the
CO2 level which is the limiting factor.
How does the amount of CO2 affect the rate of photosynthesis?
- CO2 is one of the raw materials needed for photosynthesis.
- As with light intensity the amount of C02 will only increase the rate of photosynthesis up to a point. After this the graph flattens out showing that CO2 is no longer the limiting factor.
What is one way to control the amount of CO2?
-Dissolve different amounts of sodium hydrogencarbonate in the water, which gives off CO2.
What effect does temperature have on the rate of photosynthesis?
- Usually if temperature is the limiting factor, it is because the temperature is too low - the enzymes needed for photosynthesis work more slowly at low temperatures.
- But if the plant gets too hot, the enzymes it needs for photosynthesis and it’s other reactions will be damaged.
- This happens at about 45degrees (which is pretty hot for outdoors, although greenhouses an get that hot sometimes).
What is the best way to control the temperature of the flask?
-Put the flask in a water bath.
How can you artificially create the ideal conditions for farming?
- Most common way to artificially create the ideal environment for plants is to grow them in a greenhouse.
- Greenhouses help trap the sun’s heat - make sure temperature doesn’t become the limiting factor. In winter - farmer may use heater. In summer - temperature could get too hot, so they may use shades and ventilation to cool things down.
- Commercial farmers often supply artificial light after the Sun goes down to give their plants more quality photosynthesis time.
- Farmers and gardeners can also increase the level of carbon dioxide in the greenhouse. A fairly common way is to use a paraffin heater to hear the greenhouse. As the paraffin burns, it makes carbon dioxide as a by-product.
- Keeping plants enclosed in a greenhouse makes it easier to keep them free from pests and diseases. Farmer can add fertilisers as well, to provide all the minerals needed for healthy growth.
- All this costs money - but if farmer can keep the conditions just right for photosynthesis, the plants will grow much more often, which can then be sold. It’s important that a farmer supplies just the right amount of heat, light, etc - enough to make the plants grow well, but not more than the plants need, as this would just be wasting money.
What are the 5 ways plants use glucose?
- For Respiration. This releases energy which enables them to convert the rest of the glucose into various other useful substances, which they can use to build new cells and grow. To produce some of these substances they also need to gather a few minerals from the soil.
- Making Cell Walls. Glucose is combed into cellulose for making strong cell walls, especially in a rapidly growing plant.
- Making Proteins. Glucose is combined with nitrate ions (absorbed from the soil) to make amino acids, which are then made into proteins.
- Stored in Seeds. Glucose is turned into lipids (fats and oils) for storing in seeds. Sunflower seeds, for example, contain a lot of oil - we get cooking oil and margarine from them. Seeds also store starch.
- Stored as Starch. Glucose is turned into starch and stored in roots, stems and leaves, ready for use when photosynthesis isn’t happening, like in the winter. Starch is insoluble which makes it better for storing than glucose - a cell with lots of glucose in would draw in loads of water and swell up. Potato and parsnip plants store a lot of starch underground over the winter so a new plant can grow from it the following spring. We eat the swollen storage organs.
What is the distribution of the organism?
-Where an organism is found, e.g. in a part of the playing field.
What environmental factors affect where an organism is found (the distribution of an organism)?
- Temperature.
- Availability of water.
- Availability of oxygen and carbon dioxide.
- Availability of nutrients.
- Availability of light.
Why might an organism be more common in one area than another?
-Due to differences in environmental factors between the two areas. For example, in a field, you might find that daisies are more common in the open, than under trees, because there’s more light available in the open.
What are two ways to study the distribution of an organism?
- You can measure how common an organism is in two sample areas (e.g. using quadrats) and compare them.
- You can study how the distribution changes across an area, e.g. by placing quadrats along a transect.
How do you set up comparing the population of an organism in two sample areas?
- Place a 1 m^2 quadrat on ground a random point.
- Count all organisms within the quadrat.
- Repeat steps 1-2 many times as possible.
- Wprk out mean number of organisms per quadrat within the first sample are.
- Repeat steps 1-4 in second sample area.
- Finally compare the two means.
How do you work out the population size of an organism in one sample area?
- Work out the mean number of organisms per m^2 (same as mean for 1m^2 quadrat result).
- Then multiply the mean by the total area (in m^2) of the habitat.
How do you use transacts to study the distribution of organisms along a line?
- Mark out a line in the area you want to study using a tape measure.
- Then collect data along the line.
- You can do this by just counting all the organisms you’re interested in that touch line.
- Or, you can collect data using quadrats. These can be placed next to each other along the line or at intervals, for example, every 2m.
How do you make your results reliable when collecting environmental data?
- Quadrats and transect are pretty good tools for finding out how an organism is distributed.
- But, you have to work hard to make sure your results are reliable - means making sure they are repeatable and reproducible.
- To make them more reliable, need to use a larger sample size. Bigger sample sizes = more representative of the whole population, so results using a larger sample are more likely to be reproducible.
How do you make your results valid when collecting environmental data?
- For results to be valid they must be reliable and answer the original question.
- To answer original question, need to control all the variables.
- The question you need to answer is whether a difference in distribution between two sample areas is due to a difference in distribution is caused by the environmental factor or not.
- If you don’t control the other variables you won’t know whether any correlation you’ve found is be chase of chance, because of the environmental factor you’re looking at or because of a different variable - study won’t give you valid data.
- Another way to improve validity of your results is to use random samples. If samples are all in one spot, and everywhere else is different, the results you get won’t be valid.
What do enzymes act as?
-Biological catalysts.
What do enzymes do?
-They reduce the need for high temperatures and we only have enzymes to speed up the useful chemical reactions in the body.
What is the definition for a catalyst?
-A catalyst is a substance which increases the speed of a reaction, without being changed or used up in the reaction.
What type of substance are all enzymes?
-Proteins and all proteins are made up of chains of amino acids. These chains are folded into unique shapes, which enzymes need to do their jobs.
