Chapter 15 - Modes of Reproduction Flashcards
(20 cards)
Define asexual reproduction
The process that results in the production of genetically identical offspring from one parent, without the fusion of gametes
What process does asexual reproduction involve?
Mitosis
Describe an offspring produced asexually in terms of resemblance to parent
An offspring produced asexually are genetically identical to the parent
Define mitosis
A type of cell division giving rise to genetically identical cells in which the chromosome number is maintained
Why is mitosis important?
1) For asexual reproduction to occur
2) For multicellular organisms to grow, new cells must be produced by mitosis
3) New cells are produced by mitosis to replace cells that are dead or damaged
Describe the stem tuber
- swollen end of underground stem
- many buds
- during favourable seasons, buds use food stored in tuber to grow into new plants
- many new plants as there are buds
- potato tubers are stem tubers
Describe the rhizome
- underground storage stem
- bear scale leaves and buds
- each bud grows into new plant
Describe the runner
- slender shoot that arises from a bus in parent plant
- grows horizontally over surface of soil
- buds develop along its length
- each bud develops roots and leaves, and becomes a new plant
What are advantages of asexual reproduction?
1) Only one parent is required
2) Fusion of gametes is not required
3) All beneficial qualities are passed on to the offspring
4) This method of producing offspring is faster than sexual reproduction
What are disadvantages of asexual reproduction?
1) No genetic variation in offspring
- Species are not well adapted to environment
e.g. if parent does not have resistance to a particular disease, the offspring would not have resistance to the disease, wiping the whole population of plant by a disease
Define sexual reproduction
Process involving fusion of 2 gametes to form a zygote. It produces genetically dissimilar offspring
What are the male and female gametes in humans?
Male = sperm
Female = egg
How many chromosomes are there in human gametes compared to normal body cells?
Half the number of chromosomes
What process produces gametes?
Meiosis
What are homologous chromosomes?
2 pairs of chromosomes in a cell where one chromosome in each pair is inherited from the male parent and the other from the female parent. They have the same size, shape, and the same sequence of genes
Why is meiosis a reduction division?
Each gamete contains half the number of chromosomes as the parent cell
Define meiosis
A type of cell division that gives rise to genetically dissimilar cells in which the chromosome number is halved due to the separation of homologous chromosomes
What is the difference between haploid and diploid cells?
- A haploid cell is a cell with 1 set of chromosomes
- A diploid cell is a cell with 2 sets of chromosomes
Why is meiosis important?
Meiosis produces haploid gametes
