A3.1 Diversity of organisms
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features of discontinuous variation
distinct classes or categories exist characteristics can’t be measure over a change can’t have features that fall in between categories
features of continuous variation
no distinct classes or categories characteristics can be measured and fall within a range between 2 extremes
what does the morphological species concept state
A species is a group of organisms that are morphologically unique
what does the biological species concept state
A group of organisms that can interbreed to produce fertile offspring
limitations of biological species concept
Asexual reproduction Fertile hybrids Extinction
what is a diploid cell
cell that contains two complete sets of chromosomes (2n)
what is a haploid cell
contain one complete set of chromosomes (n)
what is a centromere
a region where the 2 strands of DNA are attached
how is a karyogram made
Cells are stained and viewed under a light microscope Photographs are taken of the contents of the nucleus during metaphase of cell division The photographs of the chromosomes are cut up and arranged by size, shape, and banding pattern
asexual reproduction methods
Parthenogenesis- new individual is formed without the need for a male gamete Binary fission- in bacterial cells, grow-replicate contents- divide into 2 daughter cells Vegetative propagation
where does horizontal gene transfer occur
occurs in bacteria Genes can be transferred within a species, and even between different species
why cant a mule carry out meiosis
The fusion of a horse and a donkey gamete- a mule zygote containing 63 chromosomes These chromosomes can’t pair up during meiosis, so mules cannot produce gametes of their own