GCSE Biology (B3) Flashcards on B3, created by Anna Hollywood on 22/11/2013.
Anna Hollywood
Flashcards by Anna Hollywood, updated more than 1 year ago
Anna Hollywood
Created by Anna Hollywood almost 10 years ago

Resource summary

Question Answer
What does the number of mitochondria in a cell differ with? Amount of activity in cell. e.g. muscle cells (need to contract) and liver cells (have many functions)
What occurs in mitochondria? respiration
What is the site of photosynthesis and found in the cytoplasm? Ribosomes
What does the nucleus contain? Genes->a section of chromosome made from DNA->codes for a particular protein
What is the structure of DNA called? A double-helix
What are the complementary base pairs? A-T and C-G
What does the DNA base code control? Which protein is made
What does one gene =? One protein
Why can't the DNA leave the nucleus and what happens because of this? It is too big so it sends a copy of itself called mRNA which is small enough to fit through the nucleus' pores
What happens when the mRNA passes through the ribosome? Every 3 bases (a codon) codes for one amino acid. The ribosome helps assemble the amino acids into a chain to form a protein
What are many of the proteins made? Enzymes
What is the production of proteins called? Protein synthesis
Mitochondria use glucose for? To release ATP, which is used for all cellular processes that require energy
Who discovered DNAs structure and what 2 main pieces of data did they use? Watson and Crick. They used x-ray photographs showing that DNA had 2 strands wound in a helix. Data indicating that the bases occurred in pairs.
Why is there often such a delay between the discovery and the Nobel prize? Because other scientists need to check the study to make sure it's correct
What are the 4 types of proteins and an example? Structural proteins - collagen Hormones - insulin Carrier proteins - haemoglobin Enzymes
Why does each protein have its own number and order of amino acids? Gives each one a different shape and function
Enzymes are what type of catalyst? Biological
What is the name of the part of the enzyme where a chemical reaction takes place? Its active site
What is the enzymes matching 'key'? Substrate molecule
Explain the process of an enzyme catalysing a reaction -Enzyme forms bond with substrate molecule to form an enzyme-substrate complex -A new product is formed and the enzyme is free to catalyse more reactions
What happens if the enzyme's temperature is too low? Molecules move slower so less likely to collide
What happens if the enzyme's temperature is too high/if their pH is too low or too high? It denatures
How do you calculate how temperature alters the rate of reaction? Temperature coefficient (Q10) = rate at higher temp/rate at lower temp
What happens if mutations occur? -may lead to production of different proteins -often harmful but may have no effect -could give individual an advantage
Why are not all the same proteins made in every gene? Because different genes are switched off in different cells
Why do gene mutations affect the production of proteins? Because they can change the base code of DNA, which make the proteins
Why is respiration important? It releases ATP trapped in glucose which is used for all cellular processes that require energy
What is the word equation for aerobic respiration? glucose + oxygen --> carbon dioxide + water
What is the symbol equation for aerobic respiration? C6H12O6 + 602 --> 6CO2 + 6H2O
What is the word equation for anaerobic respiration? Glucose --> lactic acid (+energy)
Why do muscles have to use anaerobic respiration? Because sometimes muscles don't get a sufficient amount of oxygen
Where does aerobic and anaerobic respiration take place? Aerobic-mitochondria Anaerobic-cytoplasm
What are the 2 main disadvantages of anaerobic against aerobic? - Lactic acid build up causes muscle fatigue and pain -Releases less energy per glucose mlecule
What is the incomplete breakdown of glucose resulting in the build up of lactic acid called? Oxygen debt
During recovery, why does your breathing rate and heart rate stay high? So that the rapid blood flow can carry the lactic acid away to the liver. The extra oxygen can then be supplied, enabling the liver to breakdown the lactic acid.
What are the 2 ways that we can measure the rate of respiration? -How much oxygen used -The rate at which carbon dioxide is made
How do we work out the respiratory quotient? RQ = carbon dioxide produced/oxygen used
What is the metabolic rate and what does it mean if it is high? The sum of all the reactions occurring in the body. If it is high, more oxygen is needed as aerobic respiration is faster.
What can also change the respiration rate and why? Temperature and pH. They affect enzymes and respiration is controlled by enzymes
What are the 3 advantages of being multicellular? Allows us to become... -Larger -More complex -Cell differentiation
What are the 3 systems your body needs to be multicellular? -communication between all cells -supply all cells with enough nutrients -control heat and gas exchange
What is mitosis for? -Growth -To repair damaged cells -To replace worn out cells (maintenance)
What happens first in mitosis and how is this achieved? DNA replication. The double-helix structure untwists and unzips. The bases have then lost their complementary pair so form another one
What happens in mitosis after DNA replication? The chromosomes line up along the equator then the spindle fibres in the parent cell divides its chromosomes, pulling them to separate poles. The daughter cells are replicas of each other.
What is a diploid cell? Each cell have two copies of each chromosome
What is the type of cell division that produces gametes? Meiosis
Gametes are diploid/haploid Haploid
What does the fact that they are haploid ensure? That the zygote gets one copy of a gene from each parent; this ensures genetic variation
Describe the process of meiosis -The similar chromosomes pair up -They dissolve the nucleus -Cross over happens between the chromosomes so they have a bit of the other chromosome on it -The chromosomes divide (mitosis)
How is a sperm cell adapted to its function? -Many mitochondria-respiration -Acrosome-contains digestive enzymes
What 5 important things does plasma transport around the body? Glucose, carbon dioxide, hormones, antibodies, urea
Name 4 ways in which a red blood cell has adapted -Small to pass through capillaries -Biconcave(large SA:V for gas exchange) -Can combine with haemoglobin to make oxy-haemoglobin -Don't have a nucleus(more room for haemoglobin)
What are the blood vessels different jobs? Arteries-Carry blood away from the heart Veins-Carry blood to the heart Capillaries-Link arteries and veins to allow materials to pass between the blood and tissues
How are arteries adapted? Thick muscular and elastic walls to resist the high pressure
How are veins adapted? Large lumen and valves to try and keep the blood moving back to the heart due to low pressure
How are capillaries adapted? Permeable walls so substances can be transferred from blood to tissues
What type of blood do arteries carry and what is the exception? Oxygenated. The pulmonary artery.
What type of blood do veins carry and what is the exception? Deoxygenated. The pulmonary vein.
In which vessels can a pulse be felt? Arteries
What happens to the speed of the blood as it flows through the capillaries and why? -More area and the speed slows down to allow time for gas exchange
Where do the left and right atria receive blood from? The veins
Where do the left and right ventricles pump blood to? The arteries
What do the semilunar, tricuspid and bicuspid valves do? Prevent blood backflow
What are the main veins that carry blood back to the heart? The vena cava and the pulmonary vein
What are the main arteries that carry blood away from the heart? Aorta and pulmonary artery
Why does the left ventricle have a thicker muscular wall then the right ventricle? It has to pump blood all around the body and not just to the lungs
Why is it classed as a double circulatory system and what benefits does this have? The blood is pumped to the lugs and returns to the heart to be pumped around the rest of the body. Blood is at a higher pressure and so flows to the tissues at a faster rate
Which side deals with oxygenated/deoxygenated blood? Oxy-Left Deoxy-Right
How do bacterial cells differ from plant and animal cells? They lack a 'true' nucleus, mitochondria and chloroplasts
Where is the DNA found in a bacterial cell? As a singular strand/chromosome in the cytoplasm
What are the two points of rapid growth in a human's life? Just after birth and in adolescence
What is the best measure of growth? Dry mass
Why don't we always measure things in wet mass? It's difficult for some organisms like trees and organism's water content can vary over time
Why don't they use dry mass to measure growth? It involves killing the organism and doesn't measure the true growth of the whole organism
Why do different parts of the organism grow at different rates? Because different parts may be needed at different times of the organism's life
What are stem cells? Cells that can differentiate and develop into different types of cells
Where can stem cells be obtained from? Is one more used than the other and why? Embryos and adults. Embryonic stem cells are easier to find and can form a greater range of cell types.
Why are there issues with using embryonic stem cells? Because the embryos are destroyed, others think it is acceptable however as they can be used to treat life-threatening diseases
What are the four differences between plant and animal growth? Animals tend to only grow to a certain size but plants can keep growing. Plant cell division only happens in meristems (tips of roots and shoots). Main way that plants gain height is by cells enlarging rather than dividing. Plant cells can keep their ability to differentiate but animal cells lose it at an early stage.
What are the problems with selective breeding? Could lead to inbreeding, causing health problems within the species
What does inbreeding cause? Reduction in the variety of alleles in the gene pool. This can lead to increased risk of recessive alleles and a reduction in variation so the species can't adapt so easily.
What is an advantage of genetic engineering? Organisms with desired features can be produced very quickly
What is an disadvantage of genetic engineering? The inserted genes may have unexpected harmful side effects
Name 3 examples of organisms that have been genetically engineered -Rice that contains beta-carotene for vitamin A -Bacteria made to produce human insulin -Crops that are resistant to herbicides, frost damage or disease
What are the ethical issues involved with genetic engineering? -Worried about long-term side effects (that genetically engineered plants/animals will disturb natural ecosystems) -Just morally wrong
What are the 4 steps involved in genetic engineering? -Desired characteristics selected -The responsible genes are isolated -Genes are inserted into other organism -The organism reproduces
What is the process of using genetic engineering to change a person's genes and cure certain disorders? Gene therapy
What does gene therapy use? Body cells or gametes
Why is changing the genes in gametes more controversial than changing them in body cells? It could lead to 'designer babies'
What process was dolly the sheep involved in? A nuclear transfer (cloning)
What does nuclear transfer involve? Removing the nucleus from a body cell and placing it into an egg cell that has its nucleus removed
Give 3 reasons why animals could be cloned -to mass produce animals with desirable characteristics -to produce animals that have been genetically engineered to provide human products -to produce human embryos to supply stem cells for therapy
What are the ethical dilemmas concerning human cloning? They won't be 'true individuals'
What are the 5 steps in cloning? -Donor cell had its nucleus removed -Egg cell nucleus replaced with nucleus from udder cell -Egg cell electrocuted to divide it -Embryo put in mother sheep -Embryo grew into clone of sheep from which the udder cell came from
Why does cloning carry risks? Cloning animals for human products could cause diseases being spread from animals to humans
What are the 2 advantages of producing cloned plants? -Planters can be sure of plant characteristics -Can mass produce plants that are difficult to grow from seed
What are the 2 disadvantages of producing cloned plants? -If plants are susceptible to disease then all the plants will get it as they are genetically identical -Lack of genetic variation
What are the 4 steps involved in tissue culture? -Plant with certain characteristics is selected -Lots of small pieces of tissue are cut from the plant -Tissue is grown in test tubes containing a growth medium -Aseptic technique is used to ensure no microbes infect the plant
Why is cloning plants easier than cloning animals? Because their cells keep the ability to differientiate
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