Reproduction Flashcards
What is reproduction ?
Biological process where offspring are produced from parent or parents
Define asexual reproduction
Only one parent/organism that clones itself and offspring are genetically identical to parent
Define sexual reproduction
Involves two parents and combination of gametes (all offspring are unique from parents)
Why is reproduction important?
Necessary for continuity of species and is vital for evolution by natural selection
Asexual Reproduction Advantages
Reproduction is quick, no need to search for a mate and requires less energy
Asexual Reproduction Disadvantages
Genetic diseases are inherited and little to no variation of offspring (susceptible to environmental change)
Define Budding (Asexual Reproduction):
- Budding => parent forms bubble-like bud which attaches to parent while it grows and develops then breaks away
Define Binary Fission (Asexual Reproduction):
- Binary Fission => parent cell splits into two identical daughter cells
Define Fragmentation (Asexual Reproduction):
- Fragmentation => parent organism breaks into fragments and each fragment develop into a new organism
Sexual Reproduction Advantages
Provides greater variation of offspring and greater chances of species survival
Sexual Reproduction Disadvantage
Requires a mate and requires more energy
What are the 5 Kingdoms of Classification
Animals, Plants, Fungi, Bacteria, and Protists
Bacterial Traits
- Prokaryotic (no membrane-bound organelles like nucleus)
- Unicellular
What is Bacteria’s main reproduction method?
Cell Division/Binary Fission
Process of Binary Fission
- Bacterial DNA is replicated and replication occurs in both directions of the circular bacterial DNA
- Membrane pinches and 2 new cells formed
What is conjugation (Bacterial) ?
Conjugation is the non-sexual exchange/transfer of genetic material or DNA between each other
What happens during conjugation (bacterial) ?
Bacteria with certain DNA called the fertility factor use a pilus to connect to another bacterium. Once in contact, it transfers plasmid to the bacterium
What is plasmid in bacteria?
Provides extra functions, but not vital and transfer traits e.g. antibiotic resistance
Is conjugation a sexual reproduction? Why ?
No. This is because the no. of cells remains the same at the end of the process.
What are some Protist/Protista traits ?
- Eukaryotic
- Uni or multicellular but most are uni
Eukaryotes aren’t fungi, plants or animals
What are some methods of protists reproduction?
- Unicellular use budding, binary fission (asexual)
- Multicellular reproduction via. fragmentation (asexual)
Do protists reproduce via. binary fission? If so, what are the differences between bacteria?
Yes, they have a similar process, but eukaryotic protists have a nucleus, which needs to divide first.
Define multiple fission in protists ?
When the nucleus divides repeatedly before the cell splits, and the cell splits multiple times from the parent cell. Similar to binary fission, but produces more than 2 offspring.
What is budding?
Type of multiple fission, where the nucleus reproduces and smaller ‘buds’ split off the parent cell after the uneven division of cytoplasm.
What reproductive method do some multicellular algal protists use? Why?
Fragmentation. Because the algae don’t have specialized cells making it easy to break into smaller pieces and regenerate.
What are the traits of fungi?
- Eukaryotic
- Uni/Multicellular
- Heterotrophic (don’t photosynthesise)
- Decomposers of the ecosystem
How do unicellular yeasts reproduce?
Budding (asexual)
How do multicellular fungi reproduce ?
Spores (asexual)
Common reproductive method for fungi?
Spores
What is another name for spores that are asexually produced?
Mitospores
What are spores called that are sexually reproduced?
Meiospores
Can mitospores develop into an adult without fusion of another cell ?
Yes, mitospores are haploid reproductive cells and capable of developing into an adult without fusion of another cell
What allows spores to survive harsh conditions?
A layer of protective coating
What are sporangium ?
Sporangium are a cluster of spores and are released when the wall of the sporangium disintegrates
Why do fungi reproduce sexually?
Usually occurs due to adverse environmental conditions and allows for genetic variation in the population
Overview of sexual reproduction in fungi
- two haploid cells from different mycelia fuse together, where two nuclei co-exist
- haploid nuclei fuse together forming a diploid zygote
- meiosis occurs and spores are released into the environment
What is vegetative propagation?
Term describing the process where new organism results without production of seeds or spores
Example of strawberry and vegetative propagation
Strawberry plants develop a runner to move along the surface of the soil and grow a new plant once it submerges (asexual reproduction where a runner is identical to the parent plant)
How do potatoes conduct vegetative propagation?
Potato grows new plants from the eyelets of the surface of the potato
Who uses vegetative propagation and how?
Farmers/agriculturists/plant enthusiasts use more artificial ways and involve cutting parts of plants or stimulating root growth via hormones or grafting (submerging root in the substrate and allowing it to grow)
Why is asexual reproduction in plants fast?
It doesn’t require planting a seed, the seed germinating or a fragile seed growing to maturity
What is apomixis?
Asexual reproduction is where a mature plant grows from an unfertilized seed
What are petioles?
Are the structure at the base of a leaf that attaches to the stem. It can be cut here to grow another plant.
Define non-vascular plants and give an example.
A plant lacking special channels for transporting water and nutrients e.g. xylem/phloem. Examples can be mosses or liverwarts.
How do non-vascular plants reproduce?
Reproduce via. spores which develop into distinct haploid organisms before fertilisation
Define vascular plants and give an example.
Vascular plants have specialised channels e.g. xylem/phloem. Examples include ferns.
Define vascular plants and give an example.
Vascular plants have specialised channels e.g. xylem/phloem. Examples include ferns.
How many lifecycle stages do ferns have?
Ferns have 2 lifecycle stages. They produce spores which form unique structures to produce egg and sperm cells.
Summary of fern reproduction.
- Sporangium releases spores
- Spores turn into gametophytes and turns into egg/sperm cell
- Gets fertilised and forms a sporophyte
- Sporophyte develops sporangium which hangs on the underside of the fern and cycle repeats
What are gymnosperms?
Produce cones that act as their reproductive structures (no fruit protection)
Examples of gymnosperms
Cycads, conifers etc.
How do gymnosperms pollinate?
Pollinate via. wind
What is the evolutionary advantage gymnosperms have when compared to other plants?
- Don’t need to exist near water to achieve fertilisation
- Seeds provided more nourishment and protection meaning seeds can lay dormant for long periods of time before germinating
Summary of male gymnosperm sperm reproduction
- Male cone produces gametophyte (male sperm/pollen)
- Wind carries pollen to egg and fertilises the egg
- Fertilised egg develops into seed which will develop into young sporophyte
- Young sporophyte grows into adult sporophyte (tree) and produces cone
Summary of female gymnosperm egg reproduction
- Spore produces gametophyte (egg)
- Sex cell are produced in cones and is later fertilised by pollen
- Develops into young sporophyte in the seed
- Develops into an adult sporophyte (tree)
- Produces cone
What are angiosperms?
Are flowering plants producing flowers (are the reproductive structures)
How do angiosperms pollinate?
Use other organisms e.g. bird, bee, insects to serve as pollinators
How do angiosperms pollinate?
Use other organisms e.g. bird, bee, insects to serve as pollinators
What are the reproductive parts of the angiosperm called?
Stamen (male)
Pistil (female)
Can plants self-fertilise or cross-pollinate?
They can do both, but self-fertilisation is preferred for increased genetic variability
Are the male and female parts in the same plant?
Generally, but in plants, there are structures present to prevent this or even have separate male/female flowers
Is there a specific angiosperm fruit shape/size?
No, all fruits come in a variety of shapes and sizes e.g. apples, pears, grapes etc. and are all usually specialised for the kind of seed dispersal that the plant depends on
What is an example of angiosperms using specific fruit traits for reproduction?
- Bright red berries attract the attention of birds and ingest the berry, later depositing the seed miles away in their feces
- Tough nuts, squirrels will bury in the ground
Summary of male angiosperm reproduction?
- Anther develops the pollen grain (male gamete)
- Pollen grain goes down the pollen tube and into the ovary chamber
- Forms zygote
- Develops seed and eventually matures into a mature flower on sporophyte plant (2n)
Summary of female angiosperm reproduction?
- Ovule is the ovary goes through meiosis surviving megaspore (n) turns into the embryo sac
- Later when fertilised by pollen grain, forms zygote and turns into seed and then plant
Other adaptations present in flowers
- Bright colours
- Production of nectar to attract pollinators
- Structure that looks like a potential mate for a male pollinator to mate and picks up pollen
- Usage of sweet aroms and scents to attract pollinators
What are some animal traits?
- Eukaryotic
- Multicellular
- Heterotrophic
Animal Reproduction (Sexual, Asexual, or both?)
- Some capable of asexual
- All are able to sexually reproduce
Why do some animals choose sexual or asexual?
Large no. of benefits that outweigh the usefulness of asexual e.g. genetic variation
What is parthenogenesis? What are its limits?
When an egg develops into an organism without fertilisation. Only occurs in females and is asexual.
Examples of parthenogenesis?
Komodo dragon, due to the absence of mates and its tough terrains can fertilise its own egg
What is external fertilisation?
Process where egg and sperm fused outside the female body and form a diploid zygote
Disadvantages of external fertilisation
- Only possible in aquatic environments (otherwise gamete would dehydrate on land)
- Requires lots of energy
- Gametes, zygote and offspring are susceptible to environmental conditions e.g. predation, disease, environemtnal fluctuations e.g. temperature, pH etc.
Advantages of external fertilisation
- Water facilitates gamete traveling
- Produces large quantities of gametes to compensate for losses
- No need for parental care
What are examples of external fertilisation?
- Fish e.g. salmon, trout
- Frogs and toads
- Aquatic invertebrates e.g. coral, jellyfish
Explain frog reproduction
- Female frog releases unfertilised eggs into the water
- Male latches onto back and releases sperm into water
(Latching during process ensures gametes are more likely to meet)
What are the three types of fertilisation?
Oviparity
Ovoviparity
Viviparity
Oviparity definition and examples
Fertilised eggs are laid outside the female body and develop there (obtaining nutrients from yolk)
Example: chicken/lizard
Ovoviparity definition
Fertilised egg remains inside the female, but the embryo is nourished from the egg rather than the mother
Viviparity definition and example
Young develops inside the female and receives nourishment from mother
Example: Human
Advantages of internal fertilisation
- Protects egg from dehydration and other environmental risks e.g. predation, temperature
- Increases mate selection opportunities
- Higher survival rate
Disadvantages of internal fertilisation
- Reduced risk but greater cost to parents
- Fewer offspring produced
- More energy exerted
What are the three types of mammals?
Placental, Marsupial, Monotremes
What are placental mammals?
Mammals that during pregnancy have the presence of a placenta
What are placentas?
Are the sac that facilitates for exchange of nutrients and waste
What are marsupials?
Give birth to live young, which are incompletely developed and carried around in a pouch
What are monotremes?
Egg-laying mammals e.g. platypus and echidnas
Definition and function of testes?
Held in the scrotum, produce sperm and store male gametes in the epididymis
Definition and function of the accessory glands
Includes the prostate, seminal vesicle, etc. and produce secretions which make up 95% of semen
Definition and function of the vas deferns
Duct leading from the testes to the urethra
Definition and function of LH hormone
Hormone which stimulates the secretion of testosterone
Definition and function of the penis
Male organ used for delivering both semen and urine
What happens when a male reaches puberty?
Cell division occurs in the testes, resulting in the development of cells called spermatocytes. They are diploid cells that undergo meiosis to produce haploid sperm cells.
Function of the uterus
Holds the fertilised egg, which implants itself into the body part
Function of the ovaries
Gonads which hold oocytes (immature egg cells)
Function of the oviducts
Known as fallopian tubes, connects the uterus to the ovaries and give the egg a path to travel. Also the site of fertilisation.
Function of the cervix
A narrow muscular canal that connects the vagina and the uterus. It dilated during childbirth and allows the child to pass through.
Function of the vagina
Muscle lined canal which receives the male penis during sex and is also the birth canal during childbirth
What is oogenesis?
The process that starts during foetal development where a large number of cells are formed via mitosis. The cells undergo cell growth to become a primary oocyte, which begins meiosis, but stops in prophase I.
What is an oocyte?
An immature ovum/egg.
What happens to a female, during puberty?
The hormones during puberty, trigger the continued division of a single oocyte at a time. It is released and travels through the oviduct, trapped in metaphase II. If fertilised, by a sperm it continues with meiosis.
When egg cells develop, the daughter cells are uneven and only one becomes a viable egg. The others are called polar bodies.
Difference between male and female production of gametes
Male begins production of sperm during puberty, whereas oogenesis begins from the very start of life as a fetus
Are females born with all their eggs?
Yes, but the eggs are only partially developed and finish developing during puberty and fertilisation.
What triggers the change of the female gametes and what stages does it stop?
Hormones trigger the change. Hormones during puberty trigger it to finish meiosis stage I. Meiosis stage II begins but is paused until actual fertilisation.
What does FSH mean? Where is it produced? What is its function?
Follicle Stimulating Hormone. Produced by pituitary gland and helps with sexual development and functioning. Controls menstrual. cycle and growth of eggs in ovaries.
What does FSH do?
Stimulates oocytes to resume meiotic division up to metaphase II and helps with maturation into a follicle
How many eggs are viable out of the 4 daughter cells?
Only one. One oocyte becomes viable and the rest become polar bodies. The viable egg grows larger by adding nutrients and organelles
What hormone do follicles with a maturing egg release? What does it to to the female body?
Releases oestrogen. Causes changes to the endometrium (uterus lining
What is a period?
When the pregnancy is unsuccessful and the body sheds the unfertilised egg and thickened endometrium away
What is LH ? Where is it produced? What is its function?
Luteinising hormone. Produced by gland under the brain. Controls the menstrual cycle via. stimulating the release of a mature egg.
Where is Oestrogen produced and what is its role?
Produced by woman’s ovaries and eggs are the main source. Responsible for maturation and maintenance of vagina/uterus and assists in follicular development.
Where is progesterone produced? What is its role?
Secreted by corpus luteum and later placenta. Also found in ovaries and testes. It prepares the endometrium for potential pregnancy, triggers thickening lining and contractions in the uterus that would cause the body to reject an egg.
What is a follicle?
Little sac having potential to release 1 egg
What is the corpus luteum ?
It is a burst follicle that has released/no longer has an egg.
What happens to the corpus luteum and egg if unfertilised ?
Egg -> passes through uterus
Corpus luteum breaks down, stops releasing hormones and menstruation occurs
How does the sperm reach the egg’s cell membrane?
Sperm uses enzymes in the cap to dissolve and penetrate the protective layer surrounding the egg to reach the cell membrane
What does the sperm do to ensure there is species compatibility?
Molecules on the sperm surface bind to the receptors on the egg cell membrane and ensure that there is species compatibility. The nucleus from the sperm enters the egg.
What happens. once the sperm makes contact with the egg/nucleus?
The egg surface/outer egg membrane changes and hardens with chemical changes occurring to prevent further attachments to ensure that it is not fertilised by multiple sperm.
What is an ectopic pregnancy?
Pregnancy where the fertilised egg implants outside the uterus
Steps of pregnancy?
- Fertilisation
- Cleavage
- Implantation
What is cleavage?
First stage after fertilisation
- Cell rapidly reproduce via. mitosis
- Becomes a morula (2 cells)
- When 16 cells enters the uterus
- Becomes a blastocyst
What happens during implantation?
- Zygote travels down the oviduct until uterus
- Reproducing as it travels and is a blastocyst
- Implants in the uterus
- Outer layer of cells send out finger-like projections into the endometrium, developing the placenta
What is gastrulation?
The blastocyst becomes a gastrula with 3 layers of cells => becomes embryo and then foetus when basic adult features are formed
How is the umbilical cord and placenta formed?
- Placenta comes from outer layer of cells in blastocyst
- Umbilical cord develops from remnants of the yolk sac
Purpose of the placenta
Exchange organ bringing blood vessels of foetus in close contact with the maternal blood supply.
Is blood exchanged directly between the mother and foetus?
No, it is not exchanged directly but nutrients diffuse across. Similar for waste product removal.
When is a foetus called a proper foetus?
When major organs have formed at the end of the embryonic stage and distinct features are shown (8 weeks after fertilisation in humans)
What are the 3 primary layers in the gastrula?
Ectoderm
Mesoderm
Endoderm
(Supported by the yolk sac and amnion)
What does the ectoderm develop?
Epidermis, hair, PNS, brain, spinal cord
What does the mesoderm develop?
Muscle, cartilage, kidneys, gonads
What does the endoderm develop?
Lungs, bladder, digestive system
What is HCG?
Human chorionic gonadotropin, which is produced by the placenta and stimulates blood flow to pelvic area helping regulate ovarian hormones
Does the placenta produce progesterone and what does it do?
Progesterone from corpus luteum, is produced by the placenta and stimulates the preparation of the uterus and prevents lactation and contraction until birth
What is selective breeding?
Manipulation of the gene pool by choosing particular individuals that possess desired traits and passing it onto offspring
Who has been using selective breeding?
Agricultural farmers have been doing it with plants and animals
List some manipulation methods of animal/plant reproduction?
cloning, gene editing, transgenic technologies, recombinant DNA techniques
What is an example of new technology altering the traits of animals?
Genetic engineering and can be seen in transfer of genes between 2 sexually incompatible organism to form GMO’s
Steps of selective breeding?
- Determine desired trait
- Interbreed parents with desired trait
- Select offspring with best form of desired trait and interbreed them
- Continue process until population reliably produces desired trait
What is gene linkage?
Common use where certain genes are associated with each other because they exist on the same chromosome
What is an example of gene linkage?
Wheat with high grain production often carry a gene for weak stems that cannot support the wheat head.
How is selective breeding in plants done?
- Produces high quality food
- Seeds from good individuals are planted and cross-pollinated in a controlled way
What is polyploidy?
- Occurs commonly in selectively bred plants such as polyploidy
- When the plant genome isn’t 2n but 3 or even 4n
How does polyploidy occur?
Can occur through error in meiosis when a gamete is diploid rather than haploid
In plants, what happens if it is polyploid?
- Usually develops sterile offspring
- Larger and more vigorous plants with more produce
What is an example of polyploidy?
- Low fertility rates compared to diploid organisms but can be preferred due to seedless
If a plant has an even no. of chromosomes e.g. 2n, 4n or 6n can it be fertile?
Yes, as the chromosomes will separate and pair up correctly in meiosis.
What is hybridisation?
Crossing of different varieties within a species or between species/ usually more vigorous, higher yielding and greater disease resistance
Are hybrid organisms kept in the wild or agricultural environments?
Hybrid organisms are generally kept in agricultural environments and aren’t suited to life in the wild.
Example of hybrid vigour in wheat?
Special species of wheat, crossbreed of rye and wheat had initial sterile hybrids. After polyploidy was introduced, it could reproduce sexually via self-fertilisation.
Examples of selective breeding in animals
Dogs -> all came from one species of wolf, many wouldn’t survive in the wild
Poultry -> birds with best traits are selected for egg/meat production (egg and meat chickens look very different)
What is genetic modification?
Transfers genes of desirable trait to another organism and improves fertility and quality of animal products
What are simpler methods of cloning?
Grafting/cutting
Note: natural clones come from asexual reproduction
What are more advanced methods of cloning recently?
The manipulation and cloning of cells/embryos
Impact of selective breeding and genetic engineering on agriculture?
Benefits to mankind e.g. increased productivity, food production etc.
Issues can be long-term food security and animal welfare
Impacts include:
- Conservation efforts
- Food production
- Health of organisms
- Danger by altering out own DNA by eating GMO’s
- Uncontrollable pest plant speciesi
- Cross-pollination between GM and non-GM crops
- GM animals may interbreed or complete with natural populations
- Loss of biodiversity
- Evolution of new species by artificial selection
- Reduced genetic variation
- Gene Linkage
