Biology

• what is reproduction


  process in which mature living organisms give life to young ones which resemble the parents
• why do organisms reproduce


  1. to pass on genetic characteristics

  2. to continue generations

  3. to colonize new environments where they inhibit
• where does reproduction start from?


  cell division.
• what are the 2 types of cell division

  mitosis and meiosis
• What is mitosis and where does it take place?


  a type of cell division where 2 daughter cells are produced that are identical to each other. it occurs in the somatic cells.
• what are daughter cells


  the cells that are formed after cell division
• what is meiosis and where does it occur


  a type of cell division where 4 daughter cells are produced that resemble each other (aren't identical). it takes place in the gametes
• what are the two types of reproduction

  asexual and sexual
• what is asexual reproduction


  The production of genetically identical offspring from a single parent without the use of gametes. all the characteristics of the parent are passed on to all of the offspring
• why do some organisms reproduce asexually


  1. to rapidly produce identical offspring

  2. some organisms reproduce asexually when the conditions aren't favourable
• What is sexual reproduction and what happens?


  Reproduction involving 2 parent organisms and the fusion of their gametes to create diverse offspring. the fusion of the gametes causes a zygote to be produced.
• are the offspring produced in sexual reproduction genetically identical to their parents?


  no, the offspring receives some genes from each parent (23 each) meaning they CANNOT BE GENETICALLY IDENTICAL TO THEIR PARENTS.
• what are variations


  differences between individuals of the same species, caused by genetic and environmental factors
• what are mutations


  useen changes to an individual which occur either in the gene or chromosome
• what are the advantages and disadvantages of asexual reproduction


  ADVANTAGES

  1. only one parent needed

  2. rapid colonization of favourable environment

  
  

  DISADVANTAGES

  1. No variation so any change in environmental conditions will affect individual
• what are the advantages and disadvantages of sexual reproduction


  ADVANTAGES

  1. There is variation, so new features of organisms may allow adaptation to new environments

  
  

  
  

  DISADVANTAGES

  1. 2 parents needed

  2. fertilization is random so harmful variations may occur
• what is the process of pollination


  1. young plant develops reproductive organs

  2. gametes develop inside reproductive organs

  3. male gametes are transferred to the female gametes

  4. fusion of male and female gametes occur (fertilization) and zygote is produced

  5. zygote develops into embryo

  6. embryo grows into new young plant and cycle repeats
• what does hermaphrodite mean


  an organism that has both male and female reproductive organs (can refer to plants and animals)
• what are Parthenocarpic plants


  plants that reproduce asexually (without fertilization occuring)
• how are flowers formed

  they are formed with a collection of cells at the end of the flower stork which receives hormones from the main plant body which gradually develops into 4 rings of specialized leaves called a flower.
• what is the main function of flowers


  to carry out sexual reproduction in plants through the formation of male and female gametes.
• what are 3 agents of pollination


  wind, animals and water
• what is pollination and what are the 2 types


  transfer of pollen grains from anther to the stigma of the same plants or different plants. the two types are self pollination and cross pollination
• What is self-pollination?


  the pollination of a flower by pollen from the same flower or from another flower on the same plant.
• What is cross pollination?


  pollination of a flower or plant with pollen from another flower or plant.
• do human beings reproduce asexually?


  no, they reproduce sexually which involves the fusion between male and female gametes
• what happens after the fusion of male and female gametes


  enzymes break down, jelly layer/AW ;

  sperm, head/ nucleus, enters egg ;

  fertilisation membrane forms / no more sperm can enter ;

  (haploid) nuclei, fuse/join ;

  (diploid) zygote formed