Chapter Note: Reproduction | Biology for GCSE/IGCSE - Year 11 PDF Download

 Page 1


Reproduction in plants
? Reproduction is the process of making more of the same kind of organism
? There are 2 types of reproduction
? Asexual reproduction
? Sexual reproduction
? Asexual reproduction
? Asexual reproduction is the process resulting in the production of genetically identical offspring
from a single parent
? Advantages of asexual reproduction
? Quick
? Only single parent required
? Good genetic characteristics always passed on
? No dispersal so offspring will grow in the same favorable environment
? Disadvantages of asexual reproduction
? Little variation, less adaptability to changing environment
? Unlikely to withstand disease if parent not resistant
? Lack of dispersal lead to increased competition for nutrients
? Sexual reproduction
? Sexual reproduction is the process involving the fusion of 2 gametes to form a zygote. This
results in the production of offspring that is genetically different from the parents
? Gametes are sex cells that have half of the normal chromosome number (haploid)
? Therefore when male and female gamete fuse together, they form a new cell with normal
chromosome number (diploid)
? Advantages of sexual reproduction
? Variation among offspring and therefore more adaptability to a changing environment
? More likely to withstand disease
? In plants, seed dispersal reduces competition for nutrients as offspring will grow in a different
environment
? Disadvantages of sexual reproduction are
? Requires the fusion of 2 gametes
? Slower process
? Plant reproduction
? The sexual reproduction in plants involves the fusion of the male gamete (pollen) and the
female gamete (ovule)
? A plant has both a male part containing the pollen and the female part containing the ovule
? Male part - stamen
? Female part - pistil/carpel
? Sexual reproduction occurs when the pollen from
the stamen of one flower successfully reaches the
ovule of either the same flower or a different flower
? The transfer of pollen is called pollination
Page 2


Reproduction in plants
? Reproduction is the process of making more of the same kind of organism
? There are 2 types of reproduction
? Asexual reproduction
? Sexual reproduction
? Asexual reproduction
? Asexual reproduction is the process resulting in the production of genetically identical offspring
from a single parent
? Advantages of asexual reproduction
? Quick
? Only single parent required
? Good genetic characteristics always passed on
? No dispersal so offspring will grow in the same favorable environment
? Disadvantages of asexual reproduction
? Little variation, less adaptability to changing environment
? Unlikely to withstand disease if parent not resistant
? Lack of dispersal lead to increased competition for nutrients
? Sexual reproduction
? Sexual reproduction is the process involving the fusion of 2 gametes to form a zygote. This
results in the production of offspring that is genetically different from the parents
? Gametes are sex cells that have half of the normal chromosome number (haploid)
? Therefore when male and female gamete fuse together, they form a new cell with normal
chromosome number (diploid)
? Advantages of sexual reproduction
? Variation among offspring and therefore more adaptability to a changing environment
? More likely to withstand disease
? In plants, seed dispersal reduces competition for nutrients as offspring will grow in a different
environment
? Disadvantages of sexual reproduction are
? Requires the fusion of 2 gametes
? Slower process
? Plant reproduction
? The sexual reproduction in plants involves the fusion of the male gamete (pollen) and the
female gamete (ovule)
? A plant has both a male part containing the pollen and the female part containing the ovule
? Male part - stamen
? Female part - pistil/carpel
? Sexual reproduction occurs when the pollen from
the stamen of one flower successfully reaches the
ovule of either the same flower or a different flower
? The transfer of pollen is called pollination
? The carpel is the female reproductive part of the plant. It is made of 3 important structures
? Stigma - the sticky surface that catches pollen
? Style - links stigma to ovary
? Ovary - contains ovules which develop into seeds after fertilization
? The stamen is the male reproductive part of the plant. It is made of two important structures
? Anther - contains pollen
? Filament - supports the anther
? Pollination
? Pollination is the transfer of the pollen (male sex cells) from the anther to the stigma
? Once the pollen lands on the stigma, it is transferred to the ovule (female sex cell)
? The fusion of the pollen and ovule leads to what we call fertilization
? There are 2 methods by which plants facilitate pollination
? Insect pollination
? Wind pollination
? Insect pollination
? Insect pollination uses insects that land on the flower to carry pollen
? As insects move around within the flower, some pollen gets caught onto the insect's body. The
insect therefore physically carries pollen and successful pollination occurs when it rubs its body
against a stigma of the same flower or a different flower
? Wind pollination
? Wind pollination uses the wind to carry pollen
? Pollen that gets carried by the wind may end up on the stigma of the same flower or a different
flower
Page 3


Reproduction in plants
? Reproduction is the process of making more of the same kind of organism
? There are 2 types of reproduction
? Asexual reproduction
? Sexual reproduction
? Asexual reproduction
? Asexual reproduction is the process resulting in the production of genetically identical offspring
from a single parent
? Advantages of asexual reproduction
? Quick
? Only single parent required
? Good genetic characteristics always passed on
? No dispersal so offspring will grow in the same favorable environment
? Disadvantages of asexual reproduction
? Little variation, less adaptability to changing environment
? Unlikely to withstand disease if parent not resistant
? Lack of dispersal lead to increased competition for nutrients
? Sexual reproduction
? Sexual reproduction is the process involving the fusion of 2 gametes to form a zygote. This
results in the production of offspring that is genetically different from the parents
? Gametes are sex cells that have half of the normal chromosome number (haploid)
? Therefore when male and female gamete fuse together, they form a new cell with normal
chromosome number (diploid)
? Advantages of sexual reproduction
? Variation among offspring and therefore more adaptability to a changing environment
? More likely to withstand disease
? In plants, seed dispersal reduces competition for nutrients as offspring will grow in a different
environment
? Disadvantages of sexual reproduction are
? Requires the fusion of 2 gametes
? Slower process
? Plant reproduction
? The sexual reproduction in plants involves the fusion of the male gamete (pollen) and the
female gamete (ovule)
? A plant has both a male part containing the pollen and the female part containing the ovule
? Male part - stamen
? Female part - pistil/carpel
? Sexual reproduction occurs when the pollen from
the stamen of one flower successfully reaches the
ovule of either the same flower or a different flower
? The transfer of pollen is called pollination
? The carpel is the female reproductive part of the plant. It is made of 3 important structures
? Stigma - the sticky surface that catches pollen
? Style - links stigma to ovary
? Ovary - contains ovules which develop into seeds after fertilization
? The stamen is the male reproductive part of the plant. It is made of two important structures
? Anther - contains pollen
? Filament - supports the anther
? Pollination
? Pollination is the transfer of the pollen (male sex cells) from the anther to the stigma
? Once the pollen lands on the stigma, it is transferred to the ovule (female sex cell)
? The fusion of the pollen and ovule leads to what we call fertilization
? There are 2 methods by which plants facilitate pollination
? Insect pollination
? Wind pollination
? Insect pollination
? Insect pollination uses insects that land on the flower to carry pollen
? As insects move around within the flower, some pollen gets caught onto the insect's body. The
insect therefore physically carries pollen and successful pollination occurs when it rubs its body
against a stigma of the same flower or a different flower
? Wind pollination
? Wind pollination uses the wind to carry pollen
? Pollen that gets carried by the wind may end up on the stigma of the same flower or a different
flower
? Self pollination
? It is the transfer of pollen from the anther of one flower to the stigma of the same flower, or a
different flower of the same plant
? Advantages
? Only one parent required so less reliance on pollinators
? Less competition among offspring
? Disadvantages
? Less variation (since genes are all from the same plant)
? Less adaptable to changing environment and resistance to disease
? Cross pollination
? It is the transfer of pollen from the anther of one flower to the stigma of another flower on a
different plant of the same species
? Advantages
? Increased variation
? Greater adaptability to changing environment and more resistant to disease
? Disadvantages
? More reliance on pollinators
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? Fertilization
? When a pollen grain lands on the stigma of the correct
species, a pollen tube will begin to grow
? It grows through the style, enters through a small gap in
the ovary called the micropyle and eventually reaches the
ovule
? The nucleus of the pollen then passes along the pollen
tube and fuses with the nucleus resulting in successful
fertilization
? The zygote eventually develops into a seed. The seed
remains dormant until the conditions are right and
germination occurs
? Germination
? Germination is the development of a plant from a seed or spore after a period of dormancy
? The conditions that must be met for germination
¦ Water - for activation of enzymes
¦ Oxygen - for respiration for growth
¦ Temperature - optimum temperature for enzymes