2.4 Reproductive Strategies Flashcards
What are the two types of reproduction?
Sexual and asexual
What offspring does asexual reproduction produce?
Genetically identicle to each other and the parent
What offspring does sexual reproduction produce?
Genetically different from each other and the parent(s), variation
What does genetic variability allow?
It allows species to adapt to environmental change
What are the advantages of sexual reproduction?
Genetic variation allows species to adapt to changing environments
Development of a resistant stage - eg seeds - Remain as a seed during winder bc of the bad conditions and start growing in spring!
What are the disadvantages of sexual reproduction?
Slower than asexual
Because of variation, not every organism produced will be capable of survival
What are the advantages of asexual reproduction?
Quicker than sexual
- rapid population growth when conditions are favourable
- out-compete other species!
What are the disadvantages of asexual reproduction?
Lack of genetic variation
- If the environment changes, the organism is less likely to adapt to it
How are haploid and diploid cells produced?
Haploids (eg gametes) - meiosis
Diploids - mitosis
Which sex produces the larger gamete?
Females
What is fertilisation?
The fusion of the haploid sperm and haploid egg to produce a diploid zygote.
How do most aquatic organisms reproduce?
Externally
How do most terrestrial organisms reproduce?
Internally
What is internal fertilisation?
Inside the female’s body
Intromitent organ used to put sperm inside the female’s body
Sminal fluid allows sperm to be motile and prevents dehydtration
Greater chance of fertilisation
Less gametes required
What is external development?
Fertilised egg or zygote undergoes development outside the female’s body.
Eg laying eggs
Larger egg = more development = less parental care
Aminiote egg - birds and reptiles. Shell, yolk emclosing the embryo, O2 diffuses in through the shell.
What is internal development?
Development in the female’s uterus
Attatched to uterine wall via placenta / umbilical cord - allows uptake of nutrients and removal of waste
Protection
Lots of parental care - milk in mammals
What is the relationship between the degree of parental care and the number of offspring produced?
More offspring = less parental care
How do insect zygotes develop?
They develop into an intermediate form (nymph or larva) before becoming an adult.
What is complete metamorphosis?
eg Butterflies, flies
Larval stage doesn’t look like the adult
Body is completely rebuilt in the pupal stage
Reduces competition for food between larva and adults of the same species as they have different diets
What is incomplete metamorphosis?
eg Locusts
Offspring are miniature versions of the adult
They grow progressively larger in stages (instars)
How do simple plants like moss reproduce?
They require water
Secrete their gametes into the surrounding water
How do flowering plants reproduce?
Don’t require water
Pollen (male gamete) and ova (female gamete)
Insects - only used by some flowering plants
Wind - conifers (non flowering) and the rest of the flowering plants
- produce more pollen bc no guarantee it will reach another flower
Thick walls to limit dehydration
Seed = resistant stage - full of starch, lipids etc to allow the embryonic plant to develop until leaves are produced above ground (for photosynthesis)
- colonise new areas - spread them further = less competition
