3. Reproduction And Inheritance Flashcards
Sexual reproduction
- genetically varies offspring
- two parent cells involved
- fertilisation
- gamete’s produced via meiosis, followed by mitosis
Asexual reproduction
- genetically identical offspring
- one parent cell involved
- no fertilisation
- cell division by mitosis
Similarity of sexual and asexual reproduction
Both create new individuals
Alleles
An alternative form of a gene
Dominant
Allele of gene that is expressed
Recessive
Allele not expressed in phenotype when dominate allele is present
Homozygous
Both chromosomes have the same allele (tt and TT)
Heterozygous
Both contain the one of each allele (Tt and Tt)
Phenotype
The characteristic that is expressed
Genotype
Combination of the alleles
Gene
Section of a molecule of DNA that codes for a specific protein
Genome
The entire DNA of an organism
Co dominant
Both alleles are expressed in the phenotype
Pollen
Gamete produced in anther which is part of the male stamen of the flower
Ova
Gamete produced in ovules found in the ovary within the female carpel of the flower
Cross-pollination
The transfer of pollen from the anther of one flower to the stigma of another flower
Insect pollinated flower
- stamen is enclosed within flower
- stigma is enclosed within flower and sticky
- petals are large and brightly coloured
- nectaries produce sugary fluid to attract insects
Will pollinated flower
- stamen exposed outside of petal
- stigma exposed outside of petal, often feathery
- petals are small and usually green
- no nectaries
Structural adaptations of insect pollinated flowers will..
Attract insects to them and ensure insects push close to stamens/stigmas within the flower
Structural adaptations of wind pollinated flowers will..
Make sure that their stamens and stigma are exposed to the wind, achieved by having small dull coloured petals
How can plants reproduce asexually by natural methods and artificial methods
Natural method - runners (a new plant is produced where the runner twitches the ground
Artificial method - cuttings (piece of plants stem with leaves is cut from healthy plant and planted into damp composts, where it grows roots and develops into a new plant)
Role of FSH and where it’s produced
Produced - pituitary gland
Matures the egg and stimulates release of oestrogen
Role of oestrogen and where it’s produced
Produced in ovary
Thickens uterus lining ready for embryo to implant/secondary sexual characteristics
Peaks at ovulation at day 14
Stimulates release of LH and inhibits release of FSH
Role of LH and where it’s produced
Produced in pituitary gland
Stimulates ovulation and release of egg into oviduct
Role of progesterone and where it’s produced
Produced in ovary
Maintains uterus lining
Menstruation occurs
Increases after ovulation, graph drops causing shed of uterus lining
Cell produces when an egg is fertilised
Zygote
How is the developing embryo protected by amnotic fluid
Maintains constant and stable environment
Protection from jolts/injury and temperature change
How is the developing embryo protected by amnotic fluid
Maintains constant and stable environment
Protection from jolts/injury and temperature change
How does the structure of the placenta enable efficient exchange of substances between fetus and mother
- blood supply maintains concentration gradient for diffusion
- close distance between fetus blood and mother creates short diffusion distance
- villi increases surface area for diffusion
- capillary network brings nutrients to fetus and removes waste
Role of human placenta
- provide fetus with oxygen from mother
- provides nutrients from digested food (glucose + amino acids)
- removes waste products like carbon dioxide
- provides antibodies to prevent fetus from infection
- produces hormones
How do some molecules allow active transport to occur in cells of fetus
- glucose and oxygen provided used for respiration
- ATP released in respiration is used for active transport
