important Flashcards
Define sexual reproduction
Sexual reproduction is the production of new organisms by the combination of genetic information of two individuals of different species. In most species, the genetic information is carried on the chromosomes in the nucleus of reproductive cells called gametes. Gametes fuse to form a diploid zygote, which develops into a new individual.
Explain the advantages and disadvantages of sexual reproduction
The advantages of sexual reproduction is that it leads to a lot of variation within a species. As a result, the species is able to live in a variety of environmental settings. Sexual reproduction also has the ability to adapt to changes in the environment. The disadvantage is that it needs time and energy and produces a small population.
Define asexual reproduction
Asexual reproduction is the production of new organisms from single parent cell by division. Offspring are genetically identical to the parent. No mixing of male and female gametes occurs. It can happen through binary fission, budding, or fragmentation.
List the advantages and disadvantages of asexual reproduction
The disadvantage of asexual reproduction is that it has limited ability to adapt and can encounter mass die-off if the environment changes. Despite the disadvantages, the advantages of asexual reproduction are that it does not require special cells or a lot of energy. It also produces quickly, which leads to creating a large, thriving population in a stable environment.
Define allele
An alternative form of a gene, e.g, colour of an eye
Define chromosome
Chromosomes are contained in the nucleus that carries instructions for the growth and development of an organism. The chromosomes are made up of long strands of DNA and protein.
Define gene
A gene is a section of DNA that codes for a specific characteristic, e.g, the colour of an eye.
Define dominant allele
Only requires one copy of the allele to be present of the trait to be expressed
Define recessive allele
A type of allele that, when present on its own, won’t affect the individual. It requires two copies to be present for the phenotype to be expressed.
Define fertilisation
Fertilisation is defined as the union of two gametes. During fertilisation, sperm and egg cells fuse to form a diploid zygote to initiate prenatal development. The zygote develops to form an embryo.
Define zygote
A zygote is the offspring as a result of the union of two gametes. A zygote also has 46 chromosomes, 23 coming from each biological parent.
Define DNA
It contains genetic information to enable an organism to manufacture all the proteins it requires to develop and maintain an organism when necessary.
Define Mitosis
A process by which a cell replicates its chromosomes, then segregates them, produces identical nuclei in preparation for cell division.
Define meiosis
A process that contributes to genetic variety. It doesn’t make body cells; it makes gametes (reproductive cells) It’s also a process where a single parent cell divides twice to produce four cells containing half the original amount of genetic information. These four daughter cells only have half the number of chromosomes of the parent cell; they are haploid.
Define mutation
Permanent changes in the DNA sequence