Multicellular Organisms Flashcards
Name the female sex cell in animals
The egg (ovum)
Name the male sex cell in animals
The sperm
Name the male sex cell in plants
pollen
Name the female sex cell in plants
ovule
What is fertilisation
The fusion of the nucleii of the haploid gametes of two parents to create a new diploid cell
Where does fertilisation take place in animals
In the oviduct
Where does fertilisation take place in plants
In the ovary
define haploid
A cell with half a full set of chromosomes
define diploid
a cell with a full set of chromosomes
What is sexual reproduction
reproduction involving two parents that results in offspring with a set of genetic information from each
What is asexual reproduction
reproduction involving only one parent resulting in genetic clones as offspring
why is variation important
variation is needed so species are able to adapt if their environment changes
What are the pros and cons of asexual reproduction
Asexual reproduction is efficient but doesn’t allow a species to adapt
what are the pros and cons of sexual reproduction
Time consuming but the species can evolve and adapt
what plants use tubers
potatoes
what uses runners
strawberries
what uses bulbs
garlic
what uses plantlets
mexican hat plant
what are the two methods of artificial asexual reproduction for plants
cutting - section of plant inserted into soil
grafting - section of plant fitted and bound to root stock
what is cell division
a means of increasing the number of cells in an organism
why do multicelluar organisms need mitosis
for growth and repair
what is contained within two cells produced by mitosis
a complete set of chromosomes and the same genetics
step 1 of mitosis
dna is replicatiing itself, appears as fine threads in the nucleus
step 2 of mitosis
nuclear membrane begins to break down, chromosones condense and appear as double stranded in nucleus
step 3 of mitosis
chromosomes line up at the equator of cell Spindle fibres attach at the centromere
step 4 of mitosis
Spindle fibres contract, pulling chromatids apart towards the cell’s poles.
step 5 of mitosis
nuclear membranes reform around the two separate sets of single stranded chromosomes
step 6 of mitosis
cytoplasm divides, two identical daughter cells are left
what is a stem cell
an unspecialised cell. the cells in the body of a multicellular organism that carry out mitosis
where can you find stem cells
embryos (embryonic) and adult tissue (multipotent)
what are the uses of embryonic stem cells
to treat diseases such as Parkinsons or MS and for drugs testing
why is the use of embryonic stem cells controversial?
because it involves the destruction of an embryo which many believe is equivalent to murder
give an example of a nutrient required for healthy embryo development
Vitamin D for bone development, Vitamin A for eyesight etc.
what is a zygote
newly fertilised egg cell
blastocyst
16 celled embryo
foetus
embryo recognisable as baby
what substances can harm an embryo
alcohol can lead to FAS, which can cause learning difficulties, developmental issues and facial abnormalities
what do plants need to grow
light heat water
nature vs nurture
genetics vs environment
continuous variation
measured on a scale of highest to lowest, polygenic
eg. height or weight
discrete variation
can be measured categorically, due to a single gene
eg. eye colour, tongue rolling
polygenic vs single gene inheritance
many genes and environment vs one gene
genotype
the set of genes inherited
phenotype
how the genotype expresses itself physically
dominant
the allele that hides the other
the allele that is hidden
recessive
heterozygous
an individual with a copy of two alleles
homozygous
an individual with 2 copies of the same allele
alleles
different versions of the same gene
gene
a section of DNA that codes for a protein
What is another term for homozygous
True breeding
2 reasons why predicted ratios are not always achieved
Because fertilisation is a random process, because the number of offspring is not big enough
