16. Reproduction Flashcards
(94 cards)
what is asexual reproduction
the production of two genetically identical offspring from one parent
give one advantage and one disadvantage of asexual reproduction
advantage - it produces lots of offsprings quickly
disadvantage - it does not introduce variation and so all offsprings are susceptible to the same environmental pressures as the parents
what is sexual reproduction
the production of two genetically different offspring from the fusion of the nuclei from two gametes
define fertilisation
the fusion of the nuclei from two gametes
state the difference in the number of chromosomes in a gamete nucleus compared with a zygote nucleus
gametes have a haploid nucleus (23 chromosomes) whereas zygotes have a dipole nuclei (23 pairs of chromosomes)
give one advantage and one disadvantage of sexual reproduction
advantage - it introduces variation
disadvantage - it is slower and produces a limited amount of offspring
label the insect pollinated flower below
what is the function of the sepals in a plant insect pollinated plant
the sepal is a hard coating that protects the developing flower in a bud
what is the function of the petals in an insect pollinated plant
the petals attract the insects so that they can pollinate the plant
what is the function of the anthers in an insect pollinated plant
the anthers contain the pollen sacs which contain the male sex cells of the plant
what is the function of the stigma in an insect pollinated plant
these are sticky parts of the plant designed to capture the pollen grains
what is the function of the ovaries in an insect pollinated plant
they contain ovules which will grow into seeds when they are fertilized by pollen
label the diagram of a wind pollinated plant below
a - stigma
b - anthers
what type of pollen grain is this and why
pollen from an insect pollinated as it has spikes on it to make it sticky to be picked up by insects
what type of pollen grain is this and why
pollen from a wind pollinated as it is smooth so that it can be carried by the wind easily
what is pollination
where pollen grains are transferred from the anthers to the stigma
what is self pollination
where pollen grains are transferred from the anthers to th stigma of the same plant
what is cross pollination
where pollen grains are transferred from the anthers of one plant to the stigma of another plant of the same species
give one advantage of self pollination
there is a greater chance of fertilization as it does not rely on pollinators
give one disadvantage of self pollination
genetic variation decreases and the plant is less able to adapt to the environment
give one advantage of cross pollination
the plants are more able to adapt environmental changes and there is increased genetic variation
give one disadvantage of cross pollination
the plants are reliant on insect population for fertilisation
describe what happens when a pollen grain lands on the stigma of a plant
- a pollen tube grows through the style to reach the ovule in the ovary
- the nucleus from the pollen grain then travels down the pollen tube to reach the ovule
when does fertilization occur
when the nucleus of a pollen grain fuses with the nucleus of an ovule