B2 Flash Cards

Frage	Antworten
What are the Functions of the Mitochondria and Ribosomes?	Mitochondria - Where energy is released during respiration. Ribosomes - Where protein synthesis takes place.
Why are Electron microscopes used instead of light microscopes to magnify cells?	This is because electron microscopes can magnify an object by 2 million times. Light microscopes can only magnify by 2 thousand times.
Outline 1 difference between a bacterial cell and a yeast cell.	Yeast cells have a nucleus, bacteria just have their chromosomes floating around in the cytoplasm. Yeast cells have: mitochondria/ribosomes/vacuole bacterial cells do not.
How is the Goblet Cell Specialised?	This cell produces mucus which helps food to slide down the alimentary canal and prevents bacteria from getting into our lungs.
What is a virus?	A tiny microorganism, even smaller than cells, often geometric in shape. Most viruses are just made up of a sphere of protein. Many scientists still debate as to whether or not they are actually alive.
What is Diffusion?	This is the spreading of particles with a net movement frrom an area of high concentration to an area of lower concentration.
How can Visking tubing be used as a model for a cell?	It contains millions of tiny holes across its surface which only let in small particles, such as water, through. This makes it similar to a cell membrane.
How are Root Hair Cells specialised?	They have a large surface area, enabling them to absorb more water particles at once.
What is the difference between muscular tissue and glandular tissue?	Muscular tissue is specialised to produce movement. To do this it has lots of mitochondria as energy is needed for the cells to contract. Glandular tissue secretes useful substances such as enzymes and hormones.
Why do multi-cellular organisms need transport systems whilst single-celled organisms do not?	This is because a single-celled organism just has the one cell that needs oxygen, which can easily be diffused into it. On the other hand multi-cellular organisms need transport systems as otherwise many essential substances would not reach every cell on the body.
Name the 4 stages of cell groupings from cells to organ systems.	Cells > Tissues > Organs > Organ Systems
In the digestive system, what does the epithelial tissue do?	Epithelial tissue lines the whole digestive system to prevent digestive juices from damaging the body's cells. It secretes mucus which not only protects the cells, but also makes it easier for food to slide through the system.
Name where the enzymes: Amylase Protease Lipase Are secreted from in the digestive system.	Amylase: Salivary glands & pancreas Protease: Stomach & pancreas Lipase: Liver & pancreas
What are Xylem and Phloem and what do they do?	They are both transport systems for a plant. Xylem carries water from the roots to the leaves. Phloem carries sugars from the leaves to wherever they are needed.
What does the Epidermis do?	This layer helps to protect the underlying plant cells, prevent the leaves from losing too much water and it prevents pathogens from entering the plant.
What is the equation for Photosynthesis?	CARBON DIOXIDE + WATER -> GLUCOSE + OXYGEN
Why is Chlorophyll green?	This is because to perform photosynthesis the plant must be able to absorb sunlight. In a plant the chlorophyll absorbs the red and blue parts of the light spectrum and reflects the green. This makes it look green to us.
Name 3 limiting factors for Photosynthesis.	Light intensity. Carbon Dioxide concentration. Access to water.
How might keeping a tomato plant in a greenhouse enable a gardener to maximize it's prodction?	The gardener would be able to heat the greenhouse, increasing the tomato production. However they would have to be careful that their fuel consumption didnt outweigh their tomato production.
What is the chemical formula of glucose and how do plants use it to make proteins?	C6 H12 O6. To convert into proteins the plant's roots absorb nitrate ions (NO3-) from the soil. This gives the nitrogen which they can use to create protein.
What is starch and how is it stored in plants?	In plants, starch is stored as energy. It is a polymer made up of many glucose molecules. It is insoluble and forms grains in a cell instead of getting mixed up with everything else in the cell.
Name 5 factors which affect the distribution of organisms.	Temperature. Availability of Nutrients. Amount of Light. Availability of Water. Availability of Oxygen and Carbon Dioxide.
How do organisms compete with each other?	They can compete for space and light (in plants). They can also compete for food and mates (animals).
Name two ways in which you can use a quadrat to assess the amount of a species living in an area.	Count the number of species within the quadrat. Estimate the percentage of the quadrat covered by a species.
How would you choose the optimum sized quadrat with which to do your sampling?	Use each one randomly and choose the one which can contain at least one of each type of species that you are studying.
What is a protein made up of?	A long chain of amino acids.
How are proteins digested and used?	Protease enzymes break the bonds between the amino acids. These are then absorbed through the walls of the small intestine and transported via the blood to the cells which put them back together to create a specific protein required by the cell.
What is: The Active Site The Substrate The Optimum Temperature?	Active Site: the dent in an enzyme where another molecule can fit. Substrate: the molecule that fits into an enzyme's active site. Optimum temperature: the temperature at which an enzyme works best.
What are the products of: Amylase Protease Lipase?	Amylase: Sugars Protease: Amino acids Lipase: Glycerol and fatty acids.
The enzymes in the small intestine have an alkaline optimum PH. However the stomach is acidic. How does the digestive system manage this?	The liver produces bile which is alkaline. This mixes with the food when it arrives in the small intestine and neutralises the acid. It also makes the food have a slightly higher PH than 7.
Why are enzymes used in Biological detergents?	This is because some stains cannot be removed using ordinary deteregents. For example blood-stains must be removed using the enzyme protease as it is made-up of blood. This dissolves the blood molecules and washes away the stain.
Why are enzymes used to 'pre-digest' baby food?	This is because in young babies the digestive system is not fully developed yet, so having this enables them to digest the food properly.
What is the equation for Aerobic respiration?	Glucose + Oxygen -> Carbon Dioxide + Water (+ energy)
What do muscles use to produce energy for contraction?	They have large stores of Glycogen, when energy is needed the glycogen is broken down to produce glucose for respiration.
What is anaerobic respiration and what is it's equation?	Glucose -> Lactic Acid (+ a little energy). This is the incomplete breakdown of glucose and happens when your body cannot get an adequate supply of oxygen from the cells.
What does Lactic Acid do?	It builds up in the muscles and can cause cramps. This prevents the muscles from contracting properly.
What are the stages of Mitosis?	1. Chromosomes are copied and line up in the centre of the cell. 2. The identical copies of each chromosome split apartand move to opposit ends of the cell. 3. The chromosomes now form into two new nuclei. 4. New cell membranes form and two new "daughter" cells have been made from the "parent".
What are the stages of Meiosis?	1. Each chromosome is copied exactly. 2. Each chromosome then finds it's partner from the other set. 3. The chromosomes then separate from their duplicates and the cell divides. 4. Each cell divides again, giving the 4 new cells exactly half the required number of chromosomes in each nucleus. These are used to form gametes.
Name 4 types of cell that can be formed from stem cells.	Blood cells. White blood cells. Muscle cells. Fat cells.
How could stem cells be used to replace damaged tissue in the future?	Stem cells could be taken from the afflicted person's bone marrow and stimulated to start dividing into the required tissue. This could then be used to surgically replace the damaged tissue without fear of rejection.
Where do people get their chromosomes from?	Their parents. One set from each.
How can some businesses use your DNA to tell you if you could develop a disease later in life?	They would analyse the DNA's chromosomes to determine what alleles you have. Some allelles have links with certain diseases.
What did Mendel discover?	Alleles by cross-breeding plants.
What happens when a dominant allele and a recessive allele are mixed together in a gene e.g. Bb.	Only the dominant allele has any effect on the gene.
What are the chromosome pairings that determine gender?	XY: Male XX: Female Sometimes a person has 3 chromosomes, if just one of those sex chromosomes is Y, then the person is male.
Define the following terms: Genotype Phenotype Heterozygous Homozygous	Genotype: the combination of alleles. Phenotype: a characteristic. Heterozygous: two different alleles. Homozygous: two identical alleles.
What are the 4 stages of a DNA molecule?	Amino acids > Bases > Genes > DNA
How is IVF used to ensure a child is born without Cystic Fibrosis?	The embryos are screened once they have formed. This involves testing their DNA to find out if they have the alleles. Only the unaffected embryos are implanted.
How can some species be fossilized but others do not?	The conditions must be correct (there cannot be any microorganisms to decay the body). Some parts are replaced by minerals and sometimes their traces (such as footprints) are left preserved in the rock.
Name the 4 stages of Genetic speciation.	1. Geographical Isolation 2. Genetic Variation 3. Natural Selection 4. Speciation
State 2 ways which can cause extinction.	Environmental changes, New predators, New diseases or a more successful Competitor.

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