Practical 4 Flashcards
Outline the main differences between fission, budding and fragmentation (ensure that you refer to the relative size of the mother and daughter).
Fission: splitting of organism on purpose into two equal halves. Parent and daughter equal size.
Budding: small part breaks off and grows into new organism. Daughter is initially much smaller before growing to size.
What do most external fertilisers do to enhance their chances of successful fertilisation?
They release massive amounts of sperm and eggs. They release at a sironised time.
What is the role of the larval stages (including the bipinnaria larvae) in the life history of the starfish?
This stage of life is used as a dispersal stage in the development of the starfish.
How does internal fertilisation influence the number and size of the eggs compared to species that have external fertilisation?
Allows for larger eggs as well as for smaller numbers thanks to the increased chances of successful fertilisation when compared to external fertilisation.
Main advantages and disadvantages of direct development in the marine environment
The young in a direct development approach have more resources devoted to them making them more likely to survive but this is also more risky as it means more is lost if they die(K selection theory).
The immature stages of the mayfly have chewing mouthparts, but the adults have non-functional mouthparts. What does this suggest about the relative longevity and role of the two life stages in mayflies?
Adults are much shorter lived as they can not eat only live long enough to reproduce(semelparous).
role of each life stage in the life history of a hemimetabolous insect.
Nymph: food acquisition and development.
Adult: primary purpose is dispersal and reproduction
Provide a brief explanation of the role of each life stage in the life history of a holometabolous insect.
Larva: food acquisition and storage.
Pupae: development
Adult: dispersal and reproduction
What is the purpose and role of the pupa in the life cycle of a holometabolous insect?
To facilitate the development from the larval stage to that of the adult.
What are some of the potential advantages of holometabolous development compared to hemimetabolous development?
holometabolous development allows for the larva to be completely adapted to the function of food acquisition and adult stage to be completely adapted to dispersal/reproduction. It also allows the nymph and adult to live in different niches, reducing competition.
Are Garden snails gonochoristic or hermaphroditic?
hermaphroditic
What is the r-selection strategy?
r-selection strategy refers to the production of a large number of offspring (of whom only a minority may survive) as early in life as possible. Such species generally have small body size and short life spans.
what is the K-selection strategy?
A K-selection strategy generally refers to the production of a smaller number of larger and better resourced (i.e. “fitter”) offspring that have a higher probability of survival. Such species are generally late-maturing and long-lived.
What does agametic mean?
Asexual reproduction that does not involve no eggs or sperm.
What are the main forms of agametic reproduction?
fission
budding
fragmentation
