Reproduction in vertebrates Flashcards
Define reproduction
the process of producing a new generation of organisms from an existing generation
How do all vertebrates reproduce?
sexually
What does sexual reproduction involve?
The production of gametes in male and female parents
What forms when a gamete from each parent fuses?
A zygote
In order for two gametes to produce a single organism what needs to happen?
the gametes must be brought into contact with each other
developing embryo must be fed and protected
the young must survive young enough to reach sexual maturity
What do different organisms use various strategies to do?
To bring gametes into contact
To feed developing embryo
To protect developing embryo
To ensure the young survive long enough to reach sexual maturity
What do vertebrate groups carry out in different ways to ensure that it will be successful?
sexual reproduction
What are the different stages of sexual reproduction?
fertilisation
development of zygote
development of young after birth/hatching
level (or absence of) parental care
What are the possible names of an unborn baby/egg?
zygote
blastocyst
embryo
foetus
Define reproductive strategies
the way in which each animal species ensures that each stage is completed successfully
What are different adaptations that different reproductive strategies can come about from?
structural adaptations
functional adaptations
behavioural adaptations
What can improve the chances of fertilisation (or survival of the offspring)?
adaptations which ensure that reproductive strategies are completed successfully.
What happens during fertilisation?
the nucleus of a sperm cells enters the egg cell and fuses with the nucleus of the ovum
Which part of the sperm cell enters the egg cell?
the nucleus of a sperm cell enters the egg cell
What does motile mean?
able to actively move
Sperm are motile; ova are non-motile
What two things are essential for a sperm cell to successfully fertilise an egg cell?
the sperm must be protected from drying out
the sperm must be guided to the ova
Is fertilisation external or internal?
It can be both
Where does external fertilisation occur most frequently?
In most animals that breed in water
How do animals in water undergo external fertilisation?
Fish and amphibians release eggs and sperm into the water and fertilisation occurs outside the body of the female
What are some disadvantages of external fertilisation?
animals are dependent on water
large amounts of sperm and eggs required
many gametes will be eaten by predators
unstable environmental factors (temp, PH, currents)
What are some advantages of external fertilisation?
no need for parental care (reduces energy input from parents)
young are widely dispersed by currents (reduces competition)
Where do offspring that undergo external fertilisation obtain food from?
They obtain food from the environment.
This reduces energy input from parents to offspring
Where does internal fertilisation occur mainly?
in terrestrial organisms (mammals, birds, reptiles and some invertebrates)
What is an adaptation to living on land?
internal fertilisation
Where is the ovum fertilised in internal fertilisation?
inside the body of the female
Do animals that lay eggs that hatch undergo internal or external fertilisation?
internal fertilisation (the actual process of fertilisation takes place inside the female’s body)
What are some disadvantages of internal fertilisation?
there must be co-operation between the male and female so that the sperm can be placed inside the body of the female
What are some advantages of internal fertilisation?
not dependent on water
fewer gametes are produced
protection inside the body (drying out & predators)
gametes meet in a contained environment (greater chance of fertilisation)
Must organisms that have internal fertilisation be fed as they develops and grows?
yes
What are three strategies of internal fertilisation?
ovipary - animals lay eggs
ovovivipary - hatch in the body (or not long after being layed)
vivipary - give birth to live young
Do oviparous animals undergo internal or external fertilisation?
oviparous undergo internal and external fertilisation
What does oviparous mean?
eggs are laid outside a female’s body
What are eggs protected by in frogs?
a gelatinous mass
What are eggs protected by in reptiles?
a leathery shell
What are eggs protected by in birds?
hard, brittle calcareous shell
Are protective membranes present in eggs?
Yes
In oviparous animals, does the development of the embryo occur inside or outside the female’s body?
outside the females body
Where does an embryo get its food from in a oviparous animal?
from the egg yolk
What does ovoviviparous mean?
the eggs are kept inside the female’s body
How is the embryo protected in ovoviviparous animals?
By a soft shell inside the female’s body
Protective membranes are present
Where does the development of the embryo take place in ovoviviparous animals, inside of or outside of the female’s body?
Inside the females body
Where does the development of the embryo take place in viviparous animals, inside of or outside of the female’s body?
in the uterus (obviously inside the body)
Where does the embryo get its food from in ovoviviparous animals?
From the egg yolk and not from the mother
What kind of fertilisation takes place with viviparous animals?
internal fertilisation
How is the ova protected inside the females body (in a viviparous situation)?
protected by being inside body
follicle cells
membranes
uterus
How does the embryo of a viviparous animal get its food? Explain in as much detail as possible.
The embryo embeds in the uterine wall
gets food from mother via placenta and umbilical cord
What temperature is required for the young of an oviparous animal?
environmental temperature
Do offspring have much parental care with oviparous animals?
No
Birds are the only exception
What are some examples of oviparous animals?
fish amphibians reptiles birds a few mammals
What temperature are eggs/embryos kept at in the development of young ovoviviparous animals?
at a constant ideal temperature
Do ovoviviparous animals require parental care?
Sometimes
What are some examples of ovoviviparous animals?
some amphibians
some reptiles
some fish
What does gestation mean?
pregnancy
What temperature does the foetus of a viviparous animal need to be kept at?
At incubation temperature regulated by the mother
Do the offspring of viviparous animals require parental care?
Yes
suckle from mother for food
What are some examples of viviparous animals?
mammals only
What is an egg that can survive and develop on land called?
An amniotic egg
In what part of the amniotic egg does the embryo develop?
the amnion
What kind of shell does an amniotic egg have?
A calcium based shell
OR
A leathery shell
What is the advantage to amniotic egg?
They are resistant to drying out
What enables the embryo to survive out of water, in an amniotic egg?
The strong outer shell
What is an important factor to allowing reptiles to live and reproduce on land?
The amniotic egg
The amniotic egg contains a number of ___ that perform functions that are vital to the development and survival of the embryo
membranes
What provides the embryo with food in the amniotic egg?
The yolk sac
What does the amnion do?
contains amniotic fluid:
protects developing embryo
supports developing embryo
What is another name for the amnion?
The amniotic sac
What is the allantois?
A bag that collects the waste products from the embryo
Where does the chorion grow?
around the amnion, yolk and allantois
What does the chorion allow?
gaseous exchange
What do blood vessels connect in the amniotic egg?
embryo, yolk and allantois
What do blood vessels in the amniotic egg form?
a structure called the umbilical
What acts as a shock absorber in the amniotic egg?
The air space
What gives the amniotic egg protection?
The shell
What two things allow gaseous exchange in an amniotic egg?
shell and chorion
What is albumin?
The main protein that occurs in the white of an egg
What two things in an amniotic egg provide the embryo with food?
the yolk and albumin
When does an egg hatch or when is a foetus born?
Once is has reached a specific level of development
What are some examples of animals that can move around and feed themselves soon after hatching?
fish
amphibians
reptiles
What are some examples of animals that vary in the level of development in the newly-born/hatched young
birds
mammals
What two levels of development are there for newborn birds and mammals?
precocial and altricial
What does precocial mea?
The pattern of growth and development of species in which the young are relatively mature and mobile from shortly after birth or hatching
What does altricial mean?
The pattern of growth and development of species in which the young are born or hatched helpless. They cannot move around independently shortly after hatching or being born.
What are are three characteristics of precocial animals immediately once they are born/hatched?
open their eyes
hair/down present
run from predators
What are more vulnerable to predators - precocial or altricial animals?
altricial animals
