reproduction Flashcards
what is the importance of reproduction
the continuity of a species is dependent on reproduction, it is the sole biological goal
define asexual reproduction
there is only one parent that creates uniform offspring
define one parent
single organism produces offspring without fertilisation (egg and sperm)
what organisms does asexual reproduction happen in
archaea, bacteria, protista, fungi, plantae, animalia
define uniform offspring
due to an offspring inheriting all of their DNA from one parent, they are genetically identical to each other and their parent
define binary fission
a process of cell division in prokaryotes that forms two genetically identical cells
identify the steps of binary fission
- Prokaryotic cell has DNA copied
- The cell begins to grow longer, pulling the two copies apart
- The cell membrane pinches inward in the middle of the cell
- Cell splits to form two new uniform, identical offspring
what organisms undergo binary fission
bacteria and protists
define budding
a new organism grows by mitosis and cell division on the body of its parent
outline the process of budding
the parent cell undergoes mitosis which produces an identical nucleus. these move away from each other forming an outgrowth know as a bud, identical to the parent, can break off if large enough or stay attached and form a colony
what organisms undergo budding
fungi (yeast) and protists
define vegetative propagation
uniform offspring grow from a part of a parent plant
what are examples of types of vegetative propagation
runners, tubers, rhizomes, bulb, fragmentation
define runners in vegetative propagation and a organism example
parts of the parent plant touches the ground and grow roots to another area for a new uniform plant e.g. strawberries
define tuber in vegetative propagation and a organism example
swollen underground stems with buds that grow into new plants e.g. potatoes
define rhizome in vegetative propagation and a organism example
an underground horizontal stem that is capable of producing new roots and shoots of a new plant e.g. ginger
define bulb in vegetative propagation and a organism example
produce lateral buds that develop into new plants e.g. garlic
define fragmentation in vegetative propagation and a organism example
broken pieces (cuttings) of branch regenerate into identical new plants e.g. weeping willow tree
define spores under asexual processes
can be prepared mitotically (mitosis) create haploid mitospores float around land somewhere forming genetically identical organisms
define spores under sexual processes
Fungi are haploid (half set of chromosomes) and can become diploid (full set of chromosomes)
what are the advantages of asexual reproduction (at least 2)
- no time or energy wasted trying to find a mate and develop an offspring
- organisms able to rapidly reproduce a larger number of uniform offspring
- ideal to produce identical offspring when they are suited to environment
what are the disadvantages of asexual reproduction (at least 2)
- no genetic variation to adapt to selective pressures, less chance of survival in a change in the environment e.g. whole species can be wiped out by a disease
- dangerous mutations in DNA, if parent has mutation offspring also has it
- as reproduction is quick there may be limited resource and increased competition within the species
define sexual reproduction
involves the union of a male gamete (sperm) and female gamete (egg/ovum) to form a unique individual, also known as fertilisation, it allows variation
define gamete
sex cell
male: sperm
female: egg/ovum
what is the fertilisation process called for plants
pollination
what are the advantages of sexual reproduction
-genetic variation allowing a population to adapt to selective pressures
-develop plants and animals that have desirable traits
-genetic change of a species means more chance of species improvement and variation
what are the disadvantages of sexual reproduction
-metabolically expensive, offspring takes away energy that could be used for growth and repair
-mating behaviours and offspring rearing all take considerable time and resources to achieve
-can lose desirable traits
-longer time to produce fewer offspring
what is a method of sexual reproduction in bacteria
conjugation- the bacteria build a bridge, known as pili, between each cell and transfer genetic information
it divides asexually but since genes are being shared it is sexual
define external fertilisation
males and females release sperm and eggs into the environment, sperm and egg join outside the body
what organism does external fertilisation
salmon
what are the advantage of external fertilisation
doesn’t require a carrier
can produce a lot of sex cells
what are the disadvantage of external fertilisation
the selection of mate is random
requires water
egg can be destroyed by conditions or other organisms
define internal ferilsation
joining of sperm and egg inside the body after mating
define internal fertilisation external development with examples
After fertilisation, larvae (embryo) are released and development occurs outside female body e.g. barnacles
what is a larvae
embryo
what organisms undergo internal fertilisation internal development
e.g. humans, cow, cat, dog
what are the advantages of internal fertilisation
doesn’t require water
there is selection of mate therefore is not random (promotes diversity)
what are the disadvantages of internal fertilisation
The carrier of the fertilised egg is a larger target
The carrier is physically brought down throughout the pregnancy
Less sex cells are produced
what is the process of pollination (sexual reproduction) in plants
the transfer of pollen from the anther to the stigma to go down the style into the ovary to reach the ovule for the union of male and female gamete. fertilised embryo is called a seed
define self pollination
the same plants pollen reaches the stigma
define cross pollination
the different plants pollen reaches the stigma
what facilitates pollination
wind, birds, bees, flies
give an example of the areas of external fertilisation (gametes ensured, site of fertilisation, number of offspring, development of embryo)
coral
-meeting of gamete not ensured, coral releases gamete into water
-fertilisation in water
-produce a lot of offspring
-embryo developed floating in the water
give an example of the areas of internal fertilisation (gametes ensured, site of fertilisation, number of offspring, development of embryo)
cow
-meeting of gamete is ensured, gametes meet in female reproductive tract
-fertilisation in oviduct
-produce fewer offspring
-embryo developed inside uterus
define fertilisation
the union of the two gametes to make a new organism
where does fertilisation take place?
oviducts/fallopian tubes
outline the internal process that leads to fertilisation
male inserts penis into female vagina, muscular contraction pushes sperm through cervix, it then swims using their flagella into the uterus, swims to oviduct (fallopian tube) where a sperm reaches an egg, turns into zygote, undergoes mitosis forming an embryo, then a fetus
what results in the meeting of an egg and sperm
a zygote is formed
define a zygote
fusion of egg and sperm, a new diploid
what is the endometrium
uterine wall
what is the function of the ovary
produces gametes (oocyte/egg) and releases one once a month, produces oestrogen and progesterone that are responsible for sexual characteristics
what is oocyte
female gamete/egg
what is the function of the oviducts (fallopian tubes)
tubes leading from ovaries to the uterus
what is the function of the uterus
it swells to prepare for implantation and if fertilisation does not take place it releases the tissue on its inside wall as menstrual blood
what is the function of cervix
small entrance into the uterus from the vagina to allow sperm into uterus and menstrual blood out
what is the function of the vagina
Muscular tubular cavity leading to the cervix. Directs the penis towards the uterus and passage for birth/menstrual flow
define gametogenesis
makes gametes through meiosis
what is the process that makes gametes through meiosis
gametogenesis
define spermatogenesis
the process of male gamete production in animals
define oogenesis
the process of female gamete production in animals
define enzymes
speed up reaction, helps bind sperm to the egg
define acrosome
front of the sperm, contains enzymes
define zona pellucida
protective layer surrounding egg
what is the protective layer surrounding the egg called?
zona pellucida
define haploid
half set of chromosomes (23)
define diploid
full set of chromosomes (46)
outline the fertilisation steps for mammals (from when the sperm and egg meet to zygote)
- sperm uses enzymes from the acrosome to dissolve and penetrate the zona pellucida to reach the eggs cell membrane
- molecules on the sperm bind to egg cell membrance and then the nucleus of the sperm enters the cytoplasm of the egg
- changes occurs in the egg surface preventing entry of multiple sperm
- fusion of the haploid egg and sperm nuclei results in diploid zygote cell
what is the order of zygote development into a fetus
zygote, morula, blastocyst, gastrula, embryo, fetus
define cleavage
period of rapid cell division/proliferation when the single celled zygote divides into hundreds of smaller cells by mitosis
what happens with the zygote after fertilisation
After fertilisation the zygote travels toward the uterus (moves down the oviduct/fallopian tube) undergoing cleavage
what happens after the blastocyst reaches the uterus
it will embed/implant itself in the endometrium (uterine wall) this is known as implantation
what happens after the offspring undergoes cleavage
Mitotic division continues and the morula becomes a blastocysts as its cells begin to differentiate
what happens after blastocyst
gastrulation of blastocyst occurs and becomes a gastrula which has three different layers of cells (ectoderm, mesoderm and endoderm)
what happens after gastrula
it becomes a embryo and then a fetus
what are hormones
molecules produced in glands of an organism and transported in tissue fluids such as blood to stimulate specific cells or tissues into action
what is the gland, target area and function of human chorionic gonadotropin (HCG)
g:placenta (released by implanted blastocyst)
ta: ovaries
f:maintins the corpus luteum which produces progesterone and estrogen, stops ovulation/eggs from being released
what is the gland, target area and function of progesterone and estrogen
g: ovary (corpus luteum) and placenta
ta: reproductive tract and uterus
f: both inhibt hormones FSH and LH so no more eggs are released, progesterone maintains endometrium/uterine wall (so wall doesn’t shed/bleed) and prevent contractions
what is the gland, target area and function of estrogen (near birth)
g:ovary (corpus luteum)
ta: uterus
f: inhibit FSH and LH to prevent eggs being released (stop ovulation), as estrogen increases it is no longer inhibited by progesterone and therefore it initiates contractions in the muscular wall of the uterus, contractions stimulate stretch receptor signals in the brain to release oxytocin
what is the gland, target area and function of oxytocin (near birth)
g: pituitary gland (in brain)
ta: uterus and placenta
f: Stimulates the muscle of the uterine wall and contractions to stimulate stretch receptors causing more oxytocin
Contractions continue for short time after birth to eject the placenta (prostaglandins found in all cells also do)
what is the function of FSH and LH
hormones that release eggs
what is the corpus luteum
yellow sac surrounding the follicle in the ovary that has released an egg
how is the process of birth stimulated?
by the rise of estrogen levels
what is reproductive technology?
those that manipulate fertilisation and involve embryo implantation
what is selective breeding
selecting who breeds with who to continue desirable traits
what is an animal example of selective breeding?
Belgian blue cattle with highest muscle mass are selected to breed with one another
what is a plant example of selective breeding?
Artificial pollination to create Bob’s wheat variety. They crossed the pollen to the stigma of Indian wheat and Canadian fife wheat to create this wheat that can handle Australia’s harsh dry environment
what must scientist know for selective breeding
scientists must know that genes are passed through reproduction and that to reproduce an egg and sperm needs to fuse
What are the ethics of selective breeding
impact quality of life of the organisms, is right to have the power to choose who reproduce with who as it is playing a role in evolution
what is artificial insemination
involves placing semen directly into the uterus
what is artificial pollination and an example
when humans intervene with the natural pollination process. e.g. the wind of drones used to move pollination
what must scientists know for artificial insemination and pollination
Scientists must know that pollen plays the role of sperm and needs to land on the stigma and that sperm needs to enter the uterus and move up to the fallopian tube
what are the ethics about artificial insemination and pollination
impact quality of life of the organisms, is right to have the power to choose who reproduce with who as it is playing a role in evolution
what is the pros of scientific manipulation
environmental: more of a desired trait in a population
financial: farmers are able to produce desirable stock to sell
what is the cons of scientific manipulation
environmental: reducing species, Due to limited genetic variation, organisms ability to survive in changing environments are reduced
financial: obtaining organisms with desired traits can be expensive
