What is sexual reproduction?
Is the production of new living organisms by combining genetic information from two individuals of different sexes
What is asexual reproduction?
It’s a mode of reproduction, by which offspring arise from a single organism, and inherit the genes from that parent only
What are the two disadvantages of sexual reproduction?
- Only half a population are able to produce offspring
- It disrupts a successful genome from a parent as it only passes half onto each offspring
In sexually reproducing species, what is the ratio of male to female offspring?
Half male, half female
Is asexual or sexual reproduction more time efficient?
Asexual reproduction is more efficient as all offspring are able to reproduce which increases the reproduction rate in comparison to sexual reproduction, where only female offspring can reproduce
What is the paradox of the existence of males?
Males are not able to reproduce so sexually reproducing species are at a disadvantage as the number of offspring they produce is outcompeted by asexual species.
What does sexual reproduction disrupt?
The successful genomes of each parent, as the number of chromosomes must be halved to go in each gamete
How do you sexually reproducing eukaryotes halve the number of chromosomes present in each gamete?
Process of meiosis
In sexual reproduction, when are the halves of chromosomes recombined?
During fertilisation
Can you predict the alleles that will be present in each gamete?
No, this is a random process as a result of crossing over and independent assortment
Is the mating process in sexual reproduction, beneficial or not beneficial and if so why or why not? (3 points)
The mating process in sexual reproduction is not beneficial and here are three reasons why:
- Energy expenditure involved in courtship
- Energy expenditure, involved in mating
- Increase predation risk during mating, courtship, or due to sexually selected traits
What are three advantages to sexual reproduction?
- Greater genetic variation in species, maintaining a large gene pool.
- Variation means organisms can cope with selection pressures evolve to changing environmental situations.
- Provide raw material required to keep running in the red Queens arm race between parasites and hosts.
Why is sexual reproduction important?
Allows organisms to adapt to changing environments and threats, posed by predators and parasites
What is variation?
It’s the differences between individuals in a population, determined by the alleles that are inherited
When would a host be described to have greater fitness?
When it can resist and tolerate parasites
When would a parasite be described as having greater fitness?
When is able to feed and reproduce and find new hosts
Is sexual reproduction or asexual reproduction, more beneficial for hosts?
Sexual reproduction as the genetic variability of the offspring, reduces the chances that they will be susceptible to infection by parasite
When is maintaining the genome of a parent an advantage? (Asexual reproduction.)
It’s an advantage in very narrow, stable niches or when recolonising distributed habitats
What are three disadvantages to asexual reproduction?
- Offspring are genetic clones so lack variation and struggle to adapt to changes in environment. However, mutations can occur which provide some variation and so some natural selection and evolution can occur.
- It can produce lots of offspring in a small space so there is high competition for food and space.
- Unfavourable conditions such as extreme temperature can wipe out entire colonies.
What are the two types of reproduction in eukaryotes?
Vegetative cloning
- occurs in plants, using runners, bulbs, or tubers
Parthenogenesis
- Reproduction from female gamete with no fertilisation. Common in cool climates, which are disadvantages to parasites or were there is low parasite density/diversity.
What species usually use pathogenesis?
Bees, wasps and ants
Does pathogenesis occur in vertebrates?
It only occurs in one in a thousand species and is common in fish, amphibians and reptiles, but not mammals
Can species produce both asexually and sexually?
Yes, daphnia are an example. When conditions are favourable and rapid growth is needed the reproduce asexually by pathogenesis. When conditions are not favourable and there is a lack of food and poor temperature, they reproduce sexually.
Sexual reproduction allows genetic variation increasing survival.
What are three less discussed forms of asexual reproduction?
- Budding - yeast does this, it’s when offspring grow out of a parents body
- Binary fission - similar to mitosis, this is how bacteria reproduce.
- Fragmentation - fragment of plant or animal breaks off and grows into new individual, some starfish do this
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