B6 Flashcards
where in the body does meiosis take place?
testes or ovaries
what happens to the dna at the very start of meiosis, before the cells start to divide?
they duplicate
how many cell divisions are there during the process of meiosis
2
how many copies of each chromosome does the resulting cell have?
2
what type of cell division do sperm and egg cells undergo?
mitosis
where is dna located?
in the nucleus of animal and plant cells
what are chromosomes
the structures than contain DNA
what is the male gamete in animals
sperm
female gamete in animals
egg
what type of cell division is involved in the production of gametes?
meiosis
name the type of cell division used in asexual reproduction
mitosis
what name is given to the cells resulting from asexual reproduction
clones
how are oral contraceptives taken?
as a tablet
how do oral contraceptives containing multiple hormones prevent pregnancy
the hormones inhibit fsh production
what hormone is released from the contraceptive implant?
progesterone
name a berries method of contraception that can be used by women
diaphragm
name the hormone that stimulates the release of an egg
progesterone
name the hormone that stimulates sperm production
testosterone
which two hormones are involved in maintaining the uterus lining
oestrogen and progesterone
what glad secretes follicle stimulating hormone (fsh)
pituitary gland
why does a low level of fsh prevent a woman from being fertile
the egg won’t mature properly or be released properly
which hormone other than fsh will a fertility drug contain, give a reason
luteirising hormone, stimulates release of egg
two disadvantages of IVF treatment
-isnt always successful which is upsetting to the family
-often leads to multiple births which is risky for the mother
what is homeostasis?
the regulation of conditions inside the body to maintain a stable environment responding to both internal and external conditions
why are control systems important for the body?
they recognise a change from optimal conditions for cells to function properly
which component of a homeostasis control system senses blood pressure?
receptor
what is the function of the nervous system
to enact quick reactions via neurones to help save you in dangerous situations
what does DNA stand for?
deoxyribonucleic acid
how many strands is the helix in dna made up of?
2
how many chromosomes are there in a typical human cell
46
what is the 23rd pair of chromosomes
sex chromosomes
do women have xx or xy chromosomes
xx
what is a small section of DNA that codes for a specific protein
gene
what does genome mean?
the entire set of genetic material in an organism
where are the chromosomes found in a cell?
the nucleus
what are the different versions of a particular gene called
alleles
what does homozygous mean
both alleles are the same
if someone is heterozygous with one dominant allele and one recessive allele, which allele will be expressed
the dominant allele
in order to be expressed how many recessive alleles must be present?
2
what is a phenotype?
the characteristics an organism has as a result of their genotype
which process is used to create gametes
meiosis
what do we call the fusion of male and female gametes
fertilisation
during sexual reproduction in plants, which two gametes fuse together?
pollen and egg
how many parents are involved in asexual reproduction
1
when fungi and plants reproduce asexually, which process do they use?
mitosis
do bacteria reproduce via sexual or asexual reproduction
asexual
when bacteria reproduce asexually, what process do they use?
binary fission
is cystic fibrosis a dominant or recessive condition
recessive
if cystic fibrosis is a recessive condition, which genotype would result in an individual having cystic fibrosis?
homozygous recessive
what is polydactyly?
a condition in which an individual can be done with extra fingers or toes
is polydactyly cashed by a dominant or recessive allele?
dominant
which part of a human body cell is affected by cystic fibrosis
cell membrane
what does the term phenotype mean?
the observable characteristics of an organism
which two factors contribute to the variation between organisms?
-inherited genes
-environment that they are exposed to
what is a change in the DNA code called?
mutation
what factors are involved in determining body mass?
genetic factors and environmental factors
what is proof for the theory of evolution?
-fossil records
-spread of antibiotic resistance
what has been genetically engineered to produce human insulin?
bacteria
what is gene therapy?
the treatment of an inherited disorder by giving the patient a healthy copy of the faulty gene
what disorder could be treated with gene therapy?
cystic fibrosis
what part of DNA are genetically modified in bacteria?
plasmids
why have sheep been genetically engineered
to produce drugs in their milk
how does understanding genes contribute to the treatment of inherited disorders?
by tailoring treatments based on an individuals unique genetic makeup
what is the potential drawback associated with genetic screening?
possible discrimination based on genetic information
what is an explant?
a small piece of plant that can develop into a clone
two benefits of cloning via cuttings rather than micropropagation
-cutting is quicker
-cutting is cheaper
how are tissue samples removed and transferred to an agar medium
-transfer with tweezers
-cut the planet with a scalpel
give two nutrients that should be added to the agar medium and explain how it helps with plant growth
-glucose for energy and respiration
-nitrates for amino acids
-magnesium for chlorophyll
_____ are the remains of organisms from millions of years ago, which are found in rocks.
Fossils
Why are fossils used as evidence for evolution?
Fossils show us how species have changed over millions of years.
Suggest 3 ways a species could become extinct:
-A catastrophic event
-Spread of a new disease
-Introduction of a new competitor or predator
