5th yr Flashcards
what is asexual reproduction
where offspring is produced from one organism
what does asexual reprodcution not include
gametes or fertilisation
what are advantages of asexual reproduction
quick efficient and provides lots of production
what is sexual reproduction
where an nuclei of two gametes merch to form a zygote
what are the advantages of sexual reproduction
allows for variation in population
what are disadvantages of sexual reproduction
slow process
what are the advantages of a wind pollinated plant
- dull petals
- scent and nectar not produced
- long filaments
- large surface area
what are the advantages of insect pollinated plants
- colourful to attract
- sweet scent
- sticky pollen
how do wind pollinated plants work
- as the wind goes past the plant the pollen is picked up easily as the anther hang out
how do insect pollinated plants work
- when an insect land on the plant the pollen sticks to body
- when the insect visits another plant as it brushes past the stigma is deposits the pollen
how does fertilisation in plants work
- the pollen tube delivers the male nucleus to the egg
- the pollen tube grows down the style towards the ovary
- the pollen grain travels down the pollen tube to the egg and fertilises it
what are the conditions needed for germination
water
oxygen
warmth
what is fertilisation in human
the fusion of a male and female gamete to produce zygote
what are the parts of the male reproductive system
. bladder - stores urine
. glands
. sperm duct - sperm passes through here
. urethra - carries urine
. testis - produces sperm
. scrotum - supports testes
. penis- passes urine out of body
what are the parts of the female reproductive system
.oviducts- connects ovary to uterus fertilisation occurs here
.ovaries- contains ova that develop and releases hormones
.uterus - soft lining where fertilised egg is implanted to develop
.cervix- keeps foetus in place in pregnancy
. vagina - sperm is deposited here
what is the menstrual cycle stages
days 1-4 : mensuration occurs, breaking down and release of uterus lining AKA period
day 4-14 : uterus lining repairs ready for embryo
day 14 : ovulation, release of egg from ovary
day 14-28 : maintaining of the egg and cycle repeats if egg is not fertilised
what are the 4 hormones within the menstrual cycle
. Oestrogen- causes uterus wall to thick stimulates LH
. LH- causes produced in pituitary gland stimulates release of egg
. FSH - also produced in the pituitary gland
causes egg to mature, stimulates release of oestrogen
. progesterone - produced in the ovaries maintains thickness of uterus lining
what is the role of the placenta
exchange of substance between mothers blood foetus
gives : oxygen and nutrients
takes : carbon dioxide and urea
how is the placenta adapted for diffusion
. large surface area
. thin wall for efficiency
what is the amnionic fluid
protects the embryo during development by cushioning it from bumps by absorbing impact
what is a genome
then entire DNA of an organism
what is a gene
a section of a molecule of DNA that codes for a specific protein
what is located in the nucleus
chromosomes and which genes located
what is chromosome
a thread like structure composed of DNA coiled into a double helix
how many chromosome does a regular person
23 pairs so 46 chromosomes
what is a chromosome pair called
homologous pair
what is the structure of DNA
a polymer made up of a double helix formed with a phosphate, a sugar and bases
how many different types of bases are there
- thymine (T)
- adenine (A)
- guanine (G)
- cytosine (C)
What bases bind to what base in DNA
T-A
G-C
what is RNA
a long chain of nucleotides linked together
what is the difference between the bases of DNA and RNA
RNA does not contain thymine and contains uracil (U) instead
RNA are single stranded instead of double helix
what is a RNA strand made up of
alternating ribose sugars and phosphate groups linked together
what are the stages of protein synthesis
transcription = DNA is transcribed and mRNA is produced
translation = mRNA is translated and a protein is produced
what happens in transcription
- part of the DNA breaks
- exposing the strands of the gene
- mRNA nucleotides then bind to this strand
- the mRNA molecule then leaves the nucleotide
- the new strand mRNA is a complementary copy of the DNA code from the original gene
what happens in translation
- when a mRNA molecule leaves the nucleus it attaches to a ribosome
- in the cytoplasm there are free molecules called tRNA which have triplet bases, anticodon and an amino acid
- the anticodon on each tRNA molecule pairs with a complimentary codon on the mRNA
- a second tRNA molecule attaches to its complimentary codon on the mRNA and a peptide bond is formed
- this process continues until the chain coded for by the mRNA is complete
what is an allele
a variation of the same gene
how many allele are there for each gene
2
one from mother
one from father
what is a phenotype
an observational characteristic
what is a genotype
a combination of alleles that control a characteristic
what are the two the types of the alleles
dominant - only needs to be inherited from one parent for the characteristic to show
recessive- needs to be inherited from both parents for the characteristic to show
what does homozygous mean
two alleles of a gene are the same
what does heterozygous mean
two alleles of a gene are different
what does codominance mean
both alleles within a genotype are expressed
what is polygenic inheritance
characteristics that are controlled by more than one gene
what are the sex chromosomes
males - XX
females- XY
what is mitosis
when a nucleus divides into genetically identical cells
what is the process of mitosis
- each chromosome in the nuclei copies itself
- chromosomes line up along the centre of the cell
- cell fibres pull them apart to the edges
- the cell divides into 2; the new cells has a copy of each of the chromosomes
what is mitosis
the nuclear division that produces cells that are genetically different
what is the process of meiosis
- the chromosomes double and line up in the centre of the cells
- the cell then divides so one copy of each chromosomes passes to each gamete
- the chromosomes then line up in the centre and the cells fibre pulls them apart and divides again
- it repeats this until 4 daughter cells are produced
what is a diploid cell
a cell containing 2 sets of complete chromosomes (46)
what is a haploid cell
a cell that contains a single set of chromosomes (23)
what is variation
differences between individuals of the same species
what is variation caused by
difference in genes brought about by random fertilisation of gametes
environments
what is environmental variation
differences between individuals of the same species that are caused by external factors
what is an example of environmental variation
scaring due on injury
diet
plant in shade will grow tall to reach light
what is genetic variation
the differences in DNA sequences within the same species
what is mutation
random changes that occur in the sequences of DNA bases in a gene or chromosomes
how does nitrogen help crops
. nitrogen absorbed as nitrates
. nitrates help with amino acid production
. lack of amino acids leak to yellowing
how is bread made
. yeast is added to the bread dough
. the yeast produces enzymes that break down the starch in flour releasing glucose
. the yeast then begins to respire aerobically but switches to anaerobic when oxygen runs out
. when yeast carries out anaerobic respiration it produces ethanol and co2
. the co2 is trapped in small air pockets causes the dough to rise and the ethanol is evaporated
experiment for investigating anaerobic respiration in yeast
Mix yeast with sugar solution in a boiling tube
The sugar solution provides the yeast with glucose for anaerobic respiration
Carefully add a layer of oil on top of the solution
This prevents oxygen from entering the solution (prevents aerobic respiration in the yeast)
Using a capillary tube, connect this boiling tube with another boiling tube that is filled with limewater
Place the boiling tube with yeast and sugar solution into a water bath at a set temperature and count the number of bubbles produced in a fixed time (e.g. 2 minutes)
The rate that carbon dioxide is produced by yeast can be used to measure the rate of anaerobic respiration (i.e. the rate of fermentation)
Change the temperature of the water bath and repeat
what bacteria is used in the production of yoghurt
lactobacillus
what is selective breeding
when individuals/organism with desired characteristics are bred together to produced a offspring with optimum characteristics
what is genetic modifcation
the transfer of a gene from one organism to another to gain a specific characteristic
what is a restriction enzyme
used to cut the required gene out of the DNA
what is are the stages of genetic modifcation
- the gene wanted is located
- a restriction enzyme is used to cut DNA to extract the gene
- restriction enzyme also cut open a plasmid to expose its sticky ends
- the cut gene is then inserted into the enzyme plasmid using an enzyme called ligase
- the plasmid now contains the desired gene
what is a GM crop
a plan that has been genetically modified
what does transgenic mean
the transfer of genetic material from one species to another
what is the process of adult cloning
- the nucleus is removed form an unfertilised egg
- the nucleus from an adult body cells, is inserted into the egg cell
- a very small electric shock stimulates the egg to divide, via mitosis, to form an embryo
- these embryo cells contain the same genetic information as the adult cells
- when the embryo has developed into a ball of cells it inserted into the womb of a female, also known as the surrogate mother.
