B2 | Flashcards

Question	Answer
List the different parts of the animal cell and describe each of their functions	■ a nucleus, which controls the activities of the cell ■ cytoplasm, in which most of the chemical reactions take place ■ a cell membrane, controls the passage of substances into and out of the cell ■ mitochondria, which are where most energy is released in respiration ■ ribosomes, which are where protein synthesis occurs
Plant and algal cells also have a cell wall made of cellulose, which strengthens the cell, in addition to this describe 2 things that plant cells also have.	■ chloroplasts, which absorb light energy to make food ■ a permanent vacuole filled with cell sap.
Describe the structure of a bacterial cell.	A bacterial cell consists of cytoplasm and a membrane surrounded by a cell wall; the genes are not in a distinct nucleus.
Describe the structure of yeast cells.	Yeast is a single-celled organism. Yeast cells have a nucleus, cytoplasm and a membrane surrounded by a cell wall
Cells may be specialised to carry out a particular function. Describe 3 such cells.	1. red blood cells have a biconcave shape and no nucleus to increase surface area and carry more oxygen 2. Palisade cells found in the leaf have abundant chloroplasts to aid photosynthesis 3. A human egg cell is large making it a good target for the sperm and an energy reserve to provide fuel to allow it to divide
Describe what diffusion is.	Diffusion is the spreading of the particles of a gas, or of any substance in solution, resulting in a net movement from a region where they are of a higher concentration to a region with a lower concentration. The greater the difference in concentration, the faster the rate of diffusion.
Give an example of diffusion in the body.	Oxygen required for respiration passes through cell membranes by diffusion.
Describe what a tissue is an give 3 examples	A tissue is a group of cells with similar structure and function. Examples of tissues include: ■ muscular tissue, which can contract to bring about movement ■ glandular tissue, which can produce substances such as enzymes and hormones ■ epithelial tissue, which covers some parts of the body.
Describe what an organ is and describe the composition of the stomach	Organs are made of tissues. One organ may contain several tissues. The stomach is an organ that contains: ■ muscular tissue, to churn the contents ■ glandular tissue, to produce digestive juices ■ epithelial tissue, to cover the outside and the inside of the stomach.
Describe what an organ system is	Organ systems are groups of organs that perform a particular function
Describe the main parts of the digestive system.	■ glands, such as the pancreas and salivary glands, produce digestive juices ■ the stomach and small intestine, where digestion occurs ■ the liver, which produces bile ■ the small intestine, where the absorption of soluble food occurs ■ the large intestine, where water is absorbed , producing faeces.
Draw a labelled diagram of the digestive system.	Image: 16364a06-1032-4579-ab0b-1deaa0d9ef5a (image/jpg)
List 3 plant organs	Plant organs include stems, roots and leaves
Give 3 examples of plant tissues.	■ epidermal tissues, which cover the plant ■ mesophyll, which carries out photosynthesis ■ xylem and phloem, which transport substances around the plant.
Write the word equation for photosynthesis	carbon dioxide + water ==> glucose + oxygen
Describe the chemical basis of photosynthesis	■ light energy is absorbed by a green substance called chlorophyll, which is found in chloroplasts plants and algae ■ this energy is used by converting carbon dioxide (from the air) and water (from the soil) into sugar (glucose) ■ oxygen is released as a by-product.
List 3 things that can limit the rate of photosynthesis	The rate of photosynthesis may be limited by: ■ shortage of light ■ low temperature ■ shortage of carbon dioxide.
What is one way that a farmer could change the conditions in the greenhouse to give optimum conditions for photosynthesis and explain how.	Use a paraffin heater: produces heat produces light produces carbon dioxide
state 4 uses for glucose in the plant	Some glucose in plants and algae is used: ■ to produce fat or oil for storage ■ to produce cellulose, which strengthens the cell wall ■ to produce proteins ■ converted to insoluble starch for storage
In addition to glucose what else to plants require to make proteins	To produce proteins, plants also use nitrate ions that are absorbed from the soil.
State all of the physical factors that affect the distribution of living things	■ temperature ■ availability of nutrients ■ amount of light ■ availability of water ■ availability of oxygen and carbon dioxide.
State 2 ways that quantitative data on the distribution of organisms can be obtained.	Quantitative data on the distribution of organisms can be obtained by: ■ random sampling with quadrats ■ sampling along a transect.
Describe how to use a quadrat and how to improve validity and reproducibility	When using a quadrat: It should be placed randomly so that a representative sample is taken The validity and reproducibility of the results increases as the results from more quadrats are analysed
Describe what a transect is	A transect is a line across a habitat or part of a habitat. It can be as simple as a string or rope placed in a line on the ground. The number of organisms of each species can be observed and recorded at regular intervals along the transect.
Describe 4 things proteins act as.	■ structural components of tissues such as muscles ■ hormones ■ antibodies ■ catalysts
What are enzymes	Catalysts increase the rate of chemical reactions. Biological catalysts are called enzymes. Enzymes are proteins.
What is amylase ?	The enzyme amylase is produced in the salivary glands, the pancreas and the small intestine. This enzyme catalyses the breakdown of starch into sugars in the mouth and small intestine.
What are proteases ?	Protease enzymes are produced by the stomach, the pancreas and the small intestine. These enzymes catalyse the breakdown of proteins into amino acids in the stomach and the small intestine.
What are lipases ?	Lipase enzymes are produced by the pancreas and small intestine. These enzymes catalyse the breakdown of lipids (fats and oils) into fatty acids and glycerol in the small intestine.
What does the stomach produce and how does this aid digestion ?	The stomach also produces hydrochloric acid. The enzymes in the stomach work most effectively in these acid conditions.
Describe the function of bile in digestion.	The liver produces bile, which is stored in the gall bladder before being released into the small intestine. Bile neutralises the acid that is added to food in the stomach. This provides alkaline conditions in which enzymes in the small intestine work most effectively.
Describe the use of enzymes in the home	In the home: ■ biological detergents may contain protein-digesting and fat-digesting enzymes (proteases and lipases) ■ biological detergents are more effective at low temperatures than other types of detergents.
Describe the use of enzymes in industry	■ proteases are used to ‘pre-digest’ the protein in some baby foods ■ carbohydrases are used to convert starch into sugar syrup ■ isomerase is used to convert glucose syrup into fructose syrup, which is much sweeter and therefore can be used in smaller quantities in slimming foods.
Evaluate the use of enzymes in industry	In industry, enzymes are used to bring about reactions at normal temperatures and pressures that would otherwise require expensive, energy-demanding equipment. However, most enzymes are denatured at high temperatures and many are costly to produce.
Where does aerobic respiration occur ?	Most of the reactions in aerobic respiration take place inside mitochondria.
What is the word equation for respiration ?	glucose + oxygen ➞ carbon dioxide + water (+ energy)
Energy that is released during respiration is used by the organism. The energy may be used to do what ?	■ build large molecules from small ones ■ in animals, to enable muscles to contract ■ in mammals and birds, to maintain a steady body temperature in colder surroundings ■ in plants, to build up sugars, nitrates and other nutrients into amino acids which are then built up into proteins.
State 2 changes that occur during exercise	■ the heart rate increases ■ the rate and depth of breathing increases.
How and why do muscles store glucose ?	Muscles store glucose as glycogen, which can then be converted back to glucose for use during exercise
When does anaerobic respiration occur ?	During exercise, if insufficient oxygen is reaching the muscles they use anaerobic respiration to obtain energy.
What is anaerobic respiration ?	Anaerobic respiration is the incomplete breakdown of glucose and produces lactic acid.
Why does anaerobic respiration release less energy?	As the breakdown of glucose is incomplete, much less energy is released than during aerobic respiration.
What is meant by oxygen dept	Anaerobic respiration results in an oxygen debt that has to be repaid in order to oxidise lactic acid to carbon dioxide and water.
What can cause muscles to become fatigued and how is this reversed	If muscles are subjected to long periods of vigorous activity they become fatigued, ie they stop contracting efficiently. One cause of muscle fatigue is the build-up of lactic acid in the muscles. Blood flowing through the muscles removes the lactic acid.

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	Created by david doran over 7 years ago