2.2 Sexual Repro. - PLANTS Flashcards
What are plants with flowers called? Where does meiosis occur in plants - what type of tissue? What is produced as a result of meiosis (haploid_____) that contain _____?
a) Angiosperms
b) Meiosis occurs in the reproductive tissue of the plant.
c) Haploid SPORES are produced as a result of meiosis which contain gametes.
What are male spores called? Where are they held? Where are they produced? What is the female spore? Where is it produced?
a) Male spores are pollen grains held in pollen sacs that are produced in the anther of the stamen.
b) The female spore is the EMBRYO SAC that is produced in the OVARY.
What does the term ‘hermaphroditic’ mean?
Different species of flowers generically differ in their ______. Despite this we can pick out 4 main features found across most species. List those 4 features (start from the outside of the flower and work your way inwards). what two things do petals range in?
a) Hermaphrodidtic refers to flowers whom have both male and female repro. organs.
b) Species differ in the APPEARANCES.
c)
1. The outermost part of the flower is the CALYX. This structure comprises of the sepals - a protective layer specifically during the bud stage where the calyx protects the flower shoot till it’s mature.
2. The next structure is the Corolla and it coprises of the petals - petals range in both size and colour. At the base of the corrolla is the nextary which produces nectar that attracts pollinators (insects) via smell & taste.
3. After this we arrive at the stamen (the male reproductive organ) which comprises of the anther (this produces the male spores) and the anther (which holds up the anther and supplies sucrose, minerals and water through its vascular tissue to the developing pollen grians.
4. The inner part of the flower is where the female reproductive organ can be found. The carpel comprises of the stigma, style & ovary.
What happens to the pollen sacs once mature? What is the stigma & what is it held up by?
The pollen sacs dehisce, opening and releasing the pollen. The stigma is the receptive surface that is held up by the style - it’s part of the carpe (female reproductive organ).
What 2 things are pollinators such as bees attracted to? What happens as the bee enters the flower? What does its thorax and legs brush against - what sticky grain does it pick up? When the bee then enters another flower , it brushes some of the other flowers sticky _____ it picked up against the ripe _____. What form of pollination has taken place? What tow forms of pollination do we discuss in biology?
a) Bees are attracted to the scent emitted from nectar that is produced from the corrolla’s nectary and they’re also attracted to large colourful petals.
b) When a bee enters the flower its thorax and legs brush against the mature anther which causes the bee to pick up stciky pollen.
c) When the bee then enters another flower it brushes some of the other flower’s sticky pollen against the RIPE stigma.
d) The description above it for CROSS pollination.
e) In biology we learn about CROSS pollinated flowers & Wind polinated flowers.
What do wind pollinated flowers NOT need that cross pollinated flowes do in order to attract what? How are their anthers structured (i.e where are they found?) - why are they found like this in wind pollinate flowers? Wind pollinated flowers have ______ stigmas that hang _____. Their stigmas have a large _____ allowing them to catch a greater proportion of what blown in the wind?
a) They do NOT need nectar as awell as large and colourful petals that are required by cross pollinated flowers in order to attract insects.
b) The anthers are found hanging outside of the flower - this is a deliberate structure because it allows the anther’s pollen to be blown away EASILY by the wind.
c) WInd pollinated flowers have FEATHERY stigmas that hang outside the flower like the anther. They have a large SA allowing them to catch a greater proportion of pollen that’s blown by the wind.
In the anther you will find pollen sacs where the diploid (2n) mother cell undergos what? What is the tapetum (it surrounds the pollen sac)? It preforms a significant role in the formation of the ______ ____, which is _____ & resistant to ______.
a) The 2n mother cells undergo meiosis.
b) The tapetum is a layer of cells that surround the pollen sac. These cells provide nutrients and regulatory molecules to the pollen sac.
c) The tapetum plays a key role in the formation of the cell wall of the pollen. The cell wall is TOUGH and resistant to chemicals.
The cell wall plays a key role in ensuring the pollen does not suffer from ____ as well as proteting the DNA inside by not allowing ____ light to ______ thorugh which can lead to DNA ____.
a) The cell wall plays a key role in protecting the pollen from dessication allowing the pollen to be transferred to another plant without drying out.
b) Furthermore, the DNA is protected by the cell wall which doesn not allow the penetration of UV light. This ensure DNA mutations do NOT arise.
Inside the pollen grain is what that undergoes what to produce 2 nuclei a) __________ & b) __________.The what produces 2 male nuclei by mitosis? What are the male gametes in a flower? What is it not?
Inside the pollen grain is a haploid nucleus who undergoes mitosis producing 2 daughter cells a) tube nucleus & b) generative nucleus. The generative nucleus undergoes mitosis to produce 2 male nuclei. The pollen grain is NOT the male gamete.
What does the ovary contain?
The ovary contains one or more ovules.
In each ovule that is found in the ovary, what is found that undergoes MEIOSIS to make 4 haploid cells? What happens to 3 of the 4 haploid cells produced? WHat happens to the remaining one haploid cell? It undergoes how many rounds of what to produce how many haploid nuclei?
In each ovary you will find a megaspore mother cell that undergoes meiosis to make 4 haploid cells. 3 of those 4 disintegrate. The remaining one cell undergoes 3 rounds of mitosis. At the end 8 haploid nuclei are formed.
Out of the 8 haploid nuclei formed one is called the what cell or _______? 2 of the 8 do what together to make a diploid nucleus called the polar nucleus? There are 3 cells collectively called what cells? There are 2 remaining cells found on either side of the 1 cell from the first part of this question.
a) Oosphere or egg cell.
b) 2 haploid cells join together to form a DIPLOID nucleus called the POLAR NUCLEUS.
c) The 3 cells are collectively called antipodal cells.
d) The last 2 cells are called the synergids.
Summarise all of the 8 cells that evolve from the 3 rounds of mitosis that occur from the haploid cell that evolved from the meiosis of the megaspore mother cell.
a) the oosphere also called the egg cell.
b) the synergids.
c) there are 2 haploid cells who FUSE together to form a diploid nucleus called the polar nucleus.
d) the last 3 cells are called the antipodal cells.
The nuclei we discussed are surrounded by what which is a layer of cells which provide what like the tapetum that is a layer of cells the surrounds the pollen sacs in the anther? There are 2 layers of cells that are called what? There is a gap between these two called the what? What type of division directly produces the female gametes that is the same with the production of the male gametes.
a) The nucellus is a layer of cells that surrounds these nuclei and provides them with nutrients.
b) The 2 layers of cells are called the integuments.
c) The gap between the two layers of cells (integuments) is called the micropyle.
d) MItosis.
Define the term pollination. Pollination brings the what (that contain the male gametes) in contact with what that is the ____ part of the flower. This contact leads to what?
a) Pollination is the TRANSFER of pollen grains from the anther to the mature stigma of a plant of the SAME species.
b) Pollination brings together the pollen grains that contain the male gametes in contact with the female parts of the flower which results in fertilisation occuring.
What is CROSS pollination? What is SELF pollination? Which is the most used form of pollination among angiosperms?
a) CROSS pollination is the transfer of pollen from the anthers of one flower to the mature stigma of another flower of the SAME species/plant type.
b) SELF pollination is the transfer of pollen from the anthers to the mature stigma of the same plant
Now we shall look at the genetic implications of cross and self pollination. Because self fertilised species inbreed they rely on 2 things for genetic variation. Think about what 2 things may bring about variation during meiosis. These species also rely on genetic ______ to take place to bring variation to their gamete’s genomes. Which type of pollination leads to more genetic variation?
a) They rely on independent assortment (a term describing the way in which different genes seperate independently of each other during meiosis) & crossing over (the exchange of DNA material between a homologous pair of chromosomes during meiosis).
b) They also rely on MUTATIONS to occur.
c) CROSS POLLINATION
If a harmful recessive allele is possessed why is this bad for a plant who self fertilises? Think about probability…
What advantage can be noted from inbreeding? Think about preservation…
a) The probability of these two harmful recessive alleles coming together increases. There’s a greater chance/likelyhood…
b) The preservation of successful genomes well suited for a particular environment.
What is outbreeding if we’ve spoken about inbreeding. It combines the what of two different individuals? Why does outbreeding lead to more genetic variation along with the independent assortment and crossing over that occurs during the development of the gametes. Why is outbreeding better than self pollination? Think about the negatives of self pollination we’ve discussed thus far.
a) Outbreeding is the combining of two gametes from different individuals.
b) It generates more genetic variation as the two gametes do not hae the same genetic make-up.
c) Outbreeding decreases the likelyhood of producing harmful allele combinations.
Going back to cross-pollination. Plants who fertilise this way must ensure that they don’t end up fertilising themselves. There are 4 methods plants can employ to ensure cross-pollination does occur. Name them. What is the difference between protandry plants and protogyny plants - which is rarer?
a) DICHOGAMY - where the stamen (the male repro. organs - anther and filament) ripen at a different time relative to the stigma of the same plant. You can have protandry & protogyny. A protandry plant’s stamens ripen BEFORE the stigma. On the other hand a protongyny plant’s stigma ripens BEFORE the anther. Protogyny plants are rarer.
b) The position of the stamen’s anther in relation to the plant’s stigma. Plants hae their anthers BELOW the stigma in order to ensure that pollen does NOT fall onto the same plant’s STIGMA.
c) Being genetically INCOMPATIBILITY - this is where pollen from a plant cannot germinate on the same plant’s stigma i.e. they’re genetically incompatible with eachother.
d) Seperation - Male and female flowers on the same plant.
DOUBLE FERTILISATION. Firstly, define fertilisation (what is it the fusion of) Fertilisation is the fusion of a female and male gamete which produces a ZYGOTE. Where is the female gamete found in flowering plants + what’s is called ? We know that the pollen grains are haploid. Their haploid nucleus divides once by mitosis to produce two daughter cells a) tube nucleus & b) the generative nucleus. We also knwo that the generative nucleus divides by mitosis to form two male HAPLOID nuclei within the pollen grain. It is these that are delivered by the POLLEN TUBE which we shall talk about shortly.
Fertilisation is the process in which a male and female gamete fuse together to form a zygote. The female gamete is found in the ovary and is called the oosphere/egg cell.
What happens when a compatible pollen grain lands on a stigma? What solution does the stigma secrete in order for _______ to occur which is subsequently followed by what?
When a compatible pollen grain lands of a stigma the sucrose solution secreted by the stigma allows for the pollen grain to germinate and produce a pollen tube.
The pollen tube nucleus is at the tip of what? Where are the two male nuclei that were produced by the generative nucleus via mitosis positioned in relation to the pollen tube nucleus?
The pollen tube nucleus is at the tip of the pollen tube and the 2 male nuclei are behind it.
Where does the pollen tube grow out from the pollen grain - what is that gap called? The pollen tube grows up a gradient of what? ___attractants. What does the pollen tube nucleus code for the production of - what enzymes & what is their function? The pollen tube grows through the gap between the 2 layers of cells called the intugements. What is that gap called? Once the pollen tube nucleus has preformed its function what happens to it?
The pollen tube grows out of the pollen grain through a gap in the cell wall known as the pit. The pollen tube grows up a gradient of chemoattractants such as GABA emitted from the ovule. The pollen tube nucleus codes for the production of hydrolase enzymes who digest the the surrounding tissues of the style allowing the pollen tube to grow. The pollen tube grows through the micropyle and then disintegrates - presumably due to having preformed its function.
What happens to the tip of the pollen tube? What is released from the pollen tube that goes into the embryo sac? What does 1 of the 2 male nuclei do with the oosphere of the plant? What is formed? What happens to the other male nuclei? What does it fuse with if what’s remaining is the polar nucleus, 3 antipodal cells and 2 synergids? What type of nucleus is formed from the last nuclei’s fusion?
The tip of the pollen tube opens allowing the 2 male nuclei to pass through. 1 of the 2 male nuclei combines with the oosphere of the plant to produce a zygote from fertilisation/fusion of the gametes. The last male nuclei fuses with the polar nucleus (n+2n =3n) to form a triploid nucleus.
The triploid nucleus is called what? What division does it undergo? It takes over what to provide nutrition to the developing zygote/embryo?
The triploid nucleus becomes the endosperm which undergoes many rounds of mitosis to produce endosperm tissue that takes over from the nucellus in providing nutrition for the developing embryo.
Why do we call this all double fertilisation?
Because two FUSIONS have occured, one to form the zygote and one to form the endosperm!
Now we shall look at fruits & seeds. After fertilisation, the fruit & seed DEVELOP. What is the fruit & what is the seed - define them both. Where does the seed develop from and what does it contain (2 things)?
a) The fruit - a structure developing from the ovary wall, that contains 1 or more seeds.
b) The seed - a structure developed from a fertilised ovule, containing an embryo and a food store ecolsed within a ‘testa’
The diploid zygote resulting from the successful fusion of the male and female gametes then goes on to divide/ undergo WHAT? This division causes the zygote to develop into a WHAT?
The zygote divides/undergoes MITOSIS/mitiotic division forming an EMBRYO.
The embryo consists of 3 things - name them.
- Plumule - the developing shoot
- A Radicle - the developing root
- 1 or 2 COTYLEDONS - the seed leaves
What happens to the ‘3n’ triploid endosperm? It takes over WHAT becoming a WHAT? What happens to the integuments? They _____ out and become ______… They therefore become the ‘testa’. The funicle of the ovary becomes the funicle of the ____.
a) It develops into a food store taking over the nucellus and provides food for the developing embryo.
b) Integuments dry out and become waterproof they therefore become the seed coat or testa.
c) Funicle of the ovary becomes the funicle of the seed.
What happens to the ovary. What does it become? In some plant species this thing is pigmented, juicy and sweet & in others this thing is dry and hard.
The ovary becomes the FRUIT.
What is meant by the term ‘dicotyledon’? Where does the embyro lie in relation to the dicotyledon? What does the pumule become? What does the radicle become? What happens to the endosperm that was the food store for the developing embryo in the beginning?
a) The term refers to a seed with 2 seed leaves or cotyledons (2 cotyledons).
b) The embryo lies between the two cotyledons.
c) The pumule is the developing shoot.
d) The radicle becomes the plants root.
e) The endosperm which was the food store of the embryo is absorbed into the cotyledons. The seed is thus called a ‘non-endospermatic’ seed.
We have thus far looked at broad been seeds that are called dicotyledons. Now we shall look at mize seeds which are monocotyledons. What is the meaning of monocotyledon? Unlike broad been seeds whose endosperm is absorbed by the 2 cotyledons thus being classified and a ‘non-endospermatic’ seed, maize seeds are the opposite and the endosperm remains as the food store. Therefore, these seeds are called? As a result of this the cotyledon is ____ (size) and doesn’t develop further.
a) Monocotyledons have only 1 seed leaf or cotyledon.
b) ‘endospermatic’ seeds
c) Small
Seeds become DORMANT. What is the defenition of ‘dormant’? Seeds that are dormant see a reduction in their WHAT content. This does WHAT to their metabolic rate. Seeds can survive this way until conditions are suitable for growth.
a) Domant refers to seeds who suspend their actve growth and only germinate when conditions are favourable/met.
b) Reduction in water content.
c) Metabolic rate reduces.
For your information:
The developing embryo’s nutrition origionally arrives from the nucellus. This changes when the triploid endosperm is formed which then takes over the job of the nucellus. In some plants the endosperm remains - forming endospermatic seeds such as maize seeds. In some plants the endosperm is absorbed into the cotyledons and the seed is called ‘non-endospermatic’.
We shall now focus on types of seed dispersal. There are 6 types of seed dispersal. We shall look at each of the 6 over the next few cards. What is seed dispersal firstly? What is the problem of a seed germinating next to the parent plant - there are 2 reasons - explain if need be.
a) Seed dispersal is the movement of a seed AWAY from the parent plant.
b) 1. The problem with a seed germinating next to its parent is that the parent would be more successful in obtaining water and minerals from the soil in relation to the seed 2. The parent plant would be taller and thus would cast a shade over the seed. This prevents the seed from preforming photosynthesis adequately.
Briefly list all 6 types of seed dispersal.
a) Wind
b) Water
c) Rolling
d) Transport WITHIN the DIGESTIVE SYSTEM of animals
e) Bursting
f) Carrying by animals
The method of transport works by a bird for example ___ the seed which causes it to pass through the bird’s ____ tract. How is the seed therefore dispersed? What is this process called? What does the digestive system of an animal do to the seed. Think about the outer layer of the seed which is the _______? It becomes ______ by the physical ‘attack’ of the digestive enzymes present as well as the acidity of the stomach acid. Seeds can only germinate once the ____ has ______.
a) GI tract.
b) Dispersed in the faecal matter of the animal.
c) Scarification - the name of this process/method of seed dispersal
d) It weakens the testa of the seed through physical attack. A seed can only germinate once the testa has been weakened.
Rolling is another form of seed dispersal in which the fruit breaks ____ and falls to the _____ rolling away from the _____ plant. Think of a conker from a chesnut tree. The green spiky outer layer (i.e. the fruit) opens and inside is the conker (i.e. the seed).
a) Breaks open
b) Falls to the ground and rolls away from the parent plant.
Water: Which tree grows next to water on purpose for a specific reason? What are the seeds of this plant?
Coconut palm trees grow directly next to water so that when the seed - the coconut - is ready, it falls and gets whisked away by the water’s current.
We looked at transport being a method of seed dispersal. That method involved the seed moving through the GI tract of an animal and being dispersed in the faecal matter. What is the more ‘simpler’ method of seed dispersal using an animal?!
a) Carrying - a seed can hook onto the fur/coat of an animal and can thus be carried away from the parent plant.
Now we shall discuss seeds and survival. We talked about dormant seed reducing their ______ content on purpose to cease germination (because reducing the _____ content would reduce the metabolic rate) until the conditions are favourable (e.g. such as in cold weather).
a) They reduce their water content. This reduces the metabolic rate ceasing germination.
The testa of a seed is tough and resistant meaning seeds can survive adverse ______ conditions.
a) Chemical
Seeds can survive dry condition because their WHAT content is very low?
a) Water
What does the testa physically protect?
a) The embryo inside.
The endosperm or cotyledons provide WHAT until the plant can do WHAT to survive? Furthermore, seed dispersal - being taken away from the parent plant - means the survival chance of the seed is _____.
a) Nutrition until the plant can photosynthesise adequately.
b) Survival is HIGH.
There are things called ______ that cease germination until a suitable period in a year. They are broken down in cold weather so that the seed can germinate in the spring - this process is called ‘vernalisation’.
a) INHIBITORS
We shall now turn our attention to the GERMINATION process. Firstly, we must grasp the suitable conditions for seed germination. Before that however, what is the definition of germination? It is a ___________ & __________ process enabling the seed to become a __________ plant.
a) Germination is the BIOCHEMICAL and PHYSIOLOGICAL process in whih the seed become a photosynthesising plant.
Seeds only germinate when the environmental factors are favourable. The germination process begins with the very intense BIOCHEMICAL and developmental activity and ends when the first _________ ______ is produced. By this time when the first _________ ____ is produced the WHAT stores in the cotyledons or endosperm will be ______ up?
a) Ends when the first photosynthesising leaf is produced.
b) By the time the first photosynthetic leaf has formed the food stores will have been used up…
What are the 3 main requirements for germination.
a) Suitable temperature - the optimum is key for the enzymes involved in the process.
b) Water - this mobilises enzymes. It’s transported in the xylem & phloem. Water is also used to make cells TURGID.
c) OXygen - key for metabolism, growth and aerobic respiration.
Food reserves in seeds are soluble/insoluble?
Food reserves in seeds are INSOLUBLE. Therefore, they can’t be transported in solution.
If they can’t be transported directly what must be done to the reserves?
The food reserves are broken down into smaller soluble pieces that are easily trasnported in the phloem.
What enzyme hydrolyses STARCH into WHAT? Proteases hydrolyses WHAT into WHAT? Where are the products taken? What are some of the sugars converted into which goes towards the synthesis of what outer structure of the cell? What are amino acids used to synthesise?
THe products are taken to the to the meristems of both the pumule and radicle where rapid cell division occurs. Some of the sugars are converted into CELLULOSE for the CELL WALL’s synthesis. Amino acids are used to synthesise proteins.
The swollen tissues due to the water do WHAT to the testa? As a result what emerges from the seed? It’s posively geotropic and negatively phototropic… After this the WHAT emerges which is negaively geotropic but positiely phototropic?
a) Rupture the testa
b) The radicle emerges
c) The pumule emerges
Why is the pumule bent oer as it emerges from the soil upwads? It’s in the shape of a hook?
a) It protexts the tip of the pumule from soil abrasion…
