Wrong Questions - B4 to B6 Flashcards
What is the role of the carbon cycle?
- maintain the flow of nutrients and habitats
Why happens when water evaporates and condenses?
- forms water droplets which help to make clouds
Why is not all of the energy of the sun transferred to the biomass of the plant?
- only 10% is converted to body tissue by consumers
- light availability, temperature and light reflected means that half of the energy is taken away
- rest of it adds to biomass
How is energy lost by the consumers?
- excretion - urine
- egestion - not all of it is digested such as waste faeces
- respiration - movement and transferred into the surroundings as thermal energy
- not all of the organism eaten - bones or roots
How does the temperature of an area affect the organisms in an area?
- Temperature affects enzymes that control metabolic reactions
- Plants develop more
rapidly in warmer temperatures (as their metabolism will be faster), as do cold-blooded
animals (ectotherms) - Warm-blooded animals (endotherms) are less affected by their
external temperature
How are plants involved in the carbon cycle?
- take in carbon dioxide in photosynthesis
- give out carbon dioxide in respiration / when decay
- pass on carbohydrates / proteins / fats to animals / when eaten
What is the structure of a virus?
- protein coat / protein outer layer
- (containing) genetic material
What is a variation?
- difference within a species
What is a parasite?
- lives on / off / in a host / living organism
- causing it harm
How does smoking increase the risk of cancer?
- substances burnt increases the chances of mutation of the DNA sequence
What do start codons do?
- triggers transcription
- in the non - coding section of DNA
Describe the history of genetics?
- Mendel - characteristics passed on from parents, by genes, Recessive and dom
- Meischer - Nuclien = acidic substances in nucleus (DNA)
- Avery - bacteria passed on disease-causing genes from one to another
- Chargaff - same no. of C-G and A-T
- Franklin and Wilkins - photographed DNA crystals
- Watson and Crick - discovered double helix shape of DNA
- 1953 to 2000 = genetic engineering and genetic diseases
- 2003 = genome project
- now = gene therapy
How do mutations occur?
- alters the base
- inherited or spontaneous
How do plants produce seeds?
- pollen (male) fuses with the egg cell in the ovule
How does meiosis occur?
- DNA unzips, free nucleotides join, replicates
- homologous chromosomes pair together, crossed and genes swapped
- pair lines up in the centre and splits = 2 diploid cells
- 2nd div = line up and split as each arm pulled = 4 haploid gametes
- genetically varied
Where does meiosis occur?
- in gonads (testes or ovaries) = 23 from male and 23 from females
How did Darwin’s theory lead to The Theory of Evolution?
- travelled to the Galapagos Islands
- noticed that different islands had different finches
- birds were closely related, but their beaks and claws had different shapes and size
- observations = realised that the design of the finches’ beaks was linked to the food available on each island
- concluded= bird born with a beak more suited to the food available would survive longer than a bird whose beak was less suited.
- Therefore, it would have more offspring, passing on its characteristic beak.
- Over time the finch population on that island would all share this characteristic
- Darwin called this process natural selection
What is classification?
- sorting organisms into groups with similar features depending on their similarities and differences
What is the reason for using bacteria to produce hormones?
- bacteria reproduce rapidly
- can quickly produce many bacteria containing the new gene
How is malaria caused?
malaria is caused by protist, and mosquitos at as vectors and they pick it up when they feed on infected animals, every time mosquito feeds = infects by inserting protists to animal’s blood vessels = malaria can cause repeating episodes of fever and can be fatal
How do wbc eat microorganisms?
- phagocytes have a flexible membrane and have lots of enzymes
- enables them to engulf foreign cells and digest them-
- phagocytosis
How do wbc produce antibodies?
- done by B-lymphocytes
- every invading pathogen has unique antigens on its surface
- wbc comes across foreign antigen = produce proteins called antibodies to lock onto the invading cells
- antibodies are specific to that type of antigen
- antibodies are produced rapidly and carried around the body to lock on to similar pathogens
- antibodies help the phagocytes find pathogens so they can engulf them
- some wbc are called memory cells - stay around in the blood after pathogen is gone so if the person is infected with the same pathogen again = the white blood cells rapidly produce the antibodies to destroy it - naturally immune to that pathogen
What are monoclonal antibodies?
- produced from lots of clones of a single white blood cell = identical and will only target one specific protein antigen
- produced in the lab by using hybridomas (fusion of lymphocyte and tumour cell)
How are monoclonal antibodies produced?
- genetically modified mice injected with chosen antigen
- body produces antibodies to specific antigen (using lymphocytes)
- lymphocytes collected and fused with myeloma cells to make hybridoma (can’t survive out of body)
- myeloma cells reproduce indefinitely
- as hybridoma cells reproduce = form clones
- each clone will produce required antibody which is harvested = monoclonal antibodies
How do vaccinations work?
- they involve injecting dead, inactive or weakened pathogens into the body
- they carry antigens so even though they are harmless, they still trigger an immune response
- the wbc (lymphocytes) produce antibodies to attack them
- some of theses wbc remain in the blood as memory cells so if live pathogens of the same type ever appear, the antibiotics help destroy them will be produced immediately before symptoms show = immunity
What are drugs?
- substances which alter the way the body works (some medically used - penicillin and some dangerous if misused)
- this is why some can’t be bought over the counter and only on prescription
What are antibiotics?
- drugs that kill bacteria without killing your own body cells (diff types for each range of bacteria)
- many produced naturally by fungi or other microbes (penicillin = mould)
- grown at large scale and useful for clearing up bacterial infections but don’t kill viruses (not all microbes are harmful)
- some bacteria are naturally resistant to antibiotics so misuse has increased the rate of development of resistant strains and MRSA is the best-known antibiotic resistant strain
What are antivirals?
- drugs that destroy viruses (specific so act on 1 type of virus) and most stop them from reproducing
- might kill virus by = blocking virus from entering host cell, prevent virus from releasing its genetic material and prevent virus from inserting its genetic material in to host DNA
- difficult to produce as virus use the host cell to replicate so hard to target virus without damaging cell
What are antiseptics?
- chemicals that destroy microorganisms or stop them from growing and don’t harm human tissue (alcohol and iodine) = diff antiseptics for diff microorganisms
- used in external living surface (to kill/ neutralise any type of pathogen) to help clean wounds and surfaces (prevent infection rather than treat it) and kills pathogens on non-living surfaces =disinfectant (household products)
- used in hospitals and surgeries to try to prevent the spread of infections like MRSA
What happens after a potential drug is identified?
- drugs are developed further by preclinical tests in the lab to see how it behaves
- preclinical tests = test on live cells, bacteria and tissue culture
- but you can’t use human tissue to test drugs that affect whole/ multiple body systems
- e.g testing drug for blood pressure must be done with a whole animal (one with intact circulatory system)
- many fail as this stage as may damage cells or not work
What happens after clinical trials?
- Animal testing =must pass with 2 species before human trials (some think it’s cruel and others think it’s the safest way)
- 3 Rs principal:
- reduction = use a small number of animals present
- refinement = improve experiments to avoid unnecessary suffering and improve animal care
- replacement = replace animals with other techniques (e.g cell cultures)
What are the two groups of people testing drugs?
- -one is given new drug and other is given a placebo (substance that looks like the real drug but doesn’t do anything)
- this is done so scientists can see actual difference the drug makes, allowing the placebo effect
- they are double blind trials so the patient and scientist/ doctor don’t know if they’re getting the drug or the placebo until the all the results have been gathered
- this is so doctors monitoring the patients and analysing the results aren’t subconsciously influenced by their knowledge
- to allow for the placebo effect in patients (where people start to feel better just because they expect the treatment to work even though the treatment isn’t doing anything)