BY5-June2013 Flashcards
Distinguish between DNA ligase and DNA polymerase.
DNA ligase-splices/joins two sections of DNA together.
DNA polymerase-joins single nucleotides to end of a DNA chain.
Distinguish between a gene and an allele.
Gene-section of DNA which codes for a sequence of amino acids.
Allele-different-specific versions of same gene.
Distinguish between primary succession and secondary succession.
Primary succession-colonisation of an area where no living organisms have lived before.
Secondary succession-colonisation of an area where living organisms had previously lived.
Suggest why there has been little change in the phenotype and no population recovery.
Very few large cod survived.
Reduced gene pool.
No/little mutation to increase size.
Small fish produce less gametes/difficulty in breeding.
Not enough food/increased completion for food.
Change in temperature/pH.
Give two methods which are used to prevent overfishing.
Restrict fishing times/hours. Quotas. Exclusion zones. Limiting catches. Limiting season.
One solution to overfishing is aquaculture or fish farming. Give two problems associated with producing fish in this way.
Eutrophication/pollution.
Disease more likely to spread in cultivated fish.
Antibiotics need to be used, can harm other marine organisms.
Problems associated with flow of alleles into wild population.
Higher level of dioxins in farmed fish.
Suggest why triploid trout are infertile.
Three of each type of chromosome. No paring of homologous chromosomes. Prophase 1 meiosis. Meiosis doesn't take place. No gametes produced.
What is meant by the term ‘sex linkage’?
Genes on the X/Y chromosomes.
Name the hormone produced that prevents the breakdown of corpus luteum.
HCG. Human chorionic gonadotropin.
What process is involved in the production of oogonium?
Mitosis.
Suggest why only one functional female gamete is produced as a result of meiosis.
Polar bodies produced/reduction in genetic material at each stage of meiosis.
Functional gamete retains most of the cytoplasm.
Cytoplasm acts as a food store for zygote.
Needed until implantation takes place.
Briefly describe why eutrophication can result in the death of fish and many invertebrates in a river.
Algal growth/bloom.
Less light so plants die.
Bacteria/saprobionts decompose plants and increase in number.
Using up oxygen in respiration.
Explain what is meant by the term gross primary productivity.
Rate of conversion of light energy into chemical energy by producers by photosynthesis.
Explain what effect an increase in temperature has in the net primary productivity.
Net primary productivity decreases.
More carbohydrate is broken down by respiration than is produced by photosynthesis.
Give two ways by which energy is lost as it passes from one tropic level to the next.
Heat lost in respiration.
Excretion.
Not all parts eaten.
Suggest why the consumption efficiency of herbivores is much lower than that of carnivores.
Herbivores-difficult to digest cellulose, have more indigestible material in diet.
Carnivores-easily digest protein/fat, more egested material lost by herbivores/less egested materials lost by carnivores.
Tropical marine or tropical lake ecosystems generally have one or two more trophies levels than terrestrial organisms. Suggest one reason why this is the case.
Productivity of producers is higher.
Secondary productivity higher/more energy stored in consumers.
Describe the principles and techniques involved in cloning plants. Give the advantages and disadvantages of this process.
Asexually produced and genetically identical.
Artificial, cuttings.
Micropropagation.
Meristem removed.
Meristem is able to differentiate.
Cut into small pieces.
Culture under sterile conditions.
On a nutrient medium.
Cells divide to form a Callus.
Callus divided and allowed to differentiate into a plantlet.
Advantages-speed of production, production of large numbers, identical line/disease free.
Disadvantages-must remain sterile conditions to avoid introduction of pathogens, genetic instability, loss of genetic variation/reduction in gene pool.
Distinguish between seminiferous tubule and seminal vesicle.
Seminiferous tubule-meiosis sperm production/spermatogenesis.
Seminal vesicles-produce nutrient for sperms/aids sperm mobility.
