Plant Reproduction

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  • Created by: Ruhab21
  • Created on: 18-09-20 22:01
Describe the petals of insect and wind pollinated plants
1) Insects Pollinated have colourful petals that produce scent and nectar for attraction 2) Wind Pollinated that have no petals or even little and no nectar produced
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Why are they different the comparison of wind and insect of petals
Because Wind pollinated need wind for it
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Compare the anther and stigma of insect and wind pollinated flowers
1) IP have short anthers and stigma and are in the flower 2) WP have long anthers and stigma are outside the flower
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Outline the structure of a pollen sac?
Fibrous layer, tapetum and pollens
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Suggest how pollen mother cells are formed?
They are formed by mitosis
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State what do Pollen mother cells do then to form pollen grains?
They undergo meiosis to form a TETRAD of pollen which separates into POLLEN GRAINS
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State the function of a Tapetum?
Provides nutrients and causes development of pollen grains
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Suggest the importance of Tapetum?
Important in formation in pollen cell wall
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State what does a pollen grain do after being formed?
Undergoes mitosis to produce a generative and a tube nucleus
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State what happens to the generative nuclei then after another round of mitosis?
It turns into two male nuclei
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Suggest how is the exine (pollen cell wall) adapted for its function?
1) Resists Dessication (Extreme Dryness) 2) Chemically resistant
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Suggest why is it important that pollen grains are resistant to UV radiation?
So pollen is carried at 1) High Altitude 2) Without DNA mutation
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Out of Wind and Insect Pollinated which one has a higher benefit with exine and why
Wind Pollinated because pollen has to be carried in high altitude
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Outline the process of Dehiscence
1) Outer layers dry out 2) Tension caused in lateral grooves 3) Edges of pollen sacs curl away 4) An opening called Stomium exposes the pollen grains for pollination
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Suggest what helps Dehiscence in Anthers
Tapetum
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Outline process of formation of an Ovule
1) Megaspore undergoes meiosis to form 4 haploid cells 2) 3 cells degenerate 3) One cell undergoes mitotic divisions 4) An embryo sac with 2 polar bodies, 2 synergids, 3 antipodals and egg cell is formed
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State what Pollination is
The transfer of pollen grains from the anther to the stigma
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Suggest the importance of Pollination
1) So the male gametes in Pollen grains are in contact in with female parts 2) Fertilisation to occur
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Suggest what causes variation in self pollinated plants?
1) Mutation in DNA Replication in Interphase 2) Independent Assortment and Crossing over at Meiosis 1
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State the Advantages of Self Pollination?
1) Only one parent is needed for fertilisation 2) Characteristics are passed onto offsprings
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State the Disadvantages of Pollination?
1) Reduced Genetic Variation less likely to survive 2) Can be homozygous and have recessive alleles so express disease
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Suggest why cross pollination has evolutionary significance than self pollination?
Genetic Variation will give it characteristics to survive in intraspecific competition
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State what is Dichogamy? (Good way to remember is Ditch yo Gammy like Grandma)
Stamen and Stigma ripen at different times
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State why is Dichogamy important?
Inhibits Self Pollination
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State two types of Dichogamy and how to remember each of them
1) Protandry (has an which can be referred to ANTHERS) 2) Protogyny is the other one
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State what is Protandry and Protogyny
1) Protandry is when stamen ripen before stigma and Protgyny is vice versa
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Suggest why germination can't occur in plants in Protandry i.e stopping self pollination
Because stigma is not ripen so fertilisation can't occur so no germination
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Suggest why there is Genetic Incompatibility?
Pollen can't germinate on stigma
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State another way of stopping self pollination?
Anther below stigma so pollen grains can't fall on stigma
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Outline Steps of Fertilisation in Plants
1) Pollen grain releases sugary solution 2) Pollen tube nucleus germinates and forms pollen tube 3) Pollen tube releases hydrolytic enzymes and digest through style 4) Pollen tube enters through micropyle
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Outline final step of Fertilisation in Plants
5) Pollen Tube Disintegrates and releases male gametes which are released into embryo sac
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State the role of the integuments?
Physical protection
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Suggest how does the pollen tube go from the stigma to the embryo sac?
By responding to the chemo attractants secreted by the egg cell
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Describe Double Fertilisation?
1) One male gamete+ egg= diploid zygote 2) one male gamete + 2 polar bodies = triploid primary endosperm nucleus
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List some similarities between fertilisation in plants and humans (3 marks)
1) Both have fertilisation in female 2) Both use enzymes to digest their way to the female gamete 3) Both have fusion of hapliod gametes into diploid zygote
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List some differences between fertilisation in plants and humans
1) In Plants double fertilisation occurs 2) In humans male gametes can swim so no need for tube formation 3) Acrosome reaction in humans but pollen tube formation in plants
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State what does the zygote and Triploid Endosperm nucleus do and make?
Mitosis and make cotyledons and endosperm RESPECTIVELY!!!
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State what is the endosperm tissue?
Food storage tissue
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State what does Ovule form?
Seed
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State what does Ovary wall form
Fruit
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State what do Integuments form
Testa
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State what happens to Micropyle?
Pore in Testa
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State what is the function for the Fruit?
Protection
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Suggest how Testa are adapted for their function?
Chemically Resistant
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State what is a cotelydon?
Seed leaf
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What is the difference between Monocotyledons and Dicotyledons
1) Mono:- endospermic as it remains as a food store and one seed as the testa fuses with ovary wall 2) Dicotyledon :- non endospermic, cotyledon absorbs endosperm and photosynthesizes itself to obtain nutrients
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What structures are found in the diploid embryo?
Plumule , radicle and funicle
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Suggest how are dormant seeds adapted to terrestrial life?
1) Low metabolic rate so they can survive the cold 2) Low water content so survive in dry conditions
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Suggest why is seed dispersal beneficial?
1) So it reduces intra specific competition 2) Colonises new areas
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Suggest why are fruits important in seed dispersal?
1) Animals eat fruits so egest them out which disperses seeds 2)
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(Hidden Q) Suggest how seeds are adapted for dispersal? (3 marks)
1) WATER - coconut seeds can float 2) WIND - light seeds that are easily carried by wind 3) ANIMALS - Hooks to attach to animals
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State three requirements for germination? (Use Triple O mnemonic to remember)
1) O2 for respiration 2) Optimum Temperature for enzymes to work 3) H20 (OH2 just a way to remember) for mobilising enzymes
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Outline the process of germination? (3 marks)
1) Water is imbibed through micropyle 2) Cotyledons swell so the testa splits and oxygen enters for aerobic respiration 3) Food reserves from cotyledons are hydrolysed to soluble forms of transport
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Outline the final 3 steps for germination (3 marks)
4) Soluble products are transported to growing points of the embryo as energy sources for growth and respiration 5) Plumule grows upwards with a hooked tip to avoid soil erosion, and leaves unfurl 6) Radicle grows downwards into roots
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What are the food reserves that are hydrolysed in germination?
Starch, Glucose and Proteins
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What do they become?
1) Starch --> Maltose 2) Maltose --> Glucose 3) Proteins to Proteins
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Suggest what vessel are soluble products transported in plumule and radicle?
Phloem
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In terms of phototrophism, describe the change in plumule and radicle in germination
1) Plumule = Positive because they grow towards light 2) Radicle = Negative so grow away from light
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n terms of geotrophism, describe the change in plumule and radicle in germination
1) Plumule = Negative because grow against gravity 2) Radicle = Positive because grows towards gravity
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What is the name of the hormone for germination control?
Gibberellin
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Explain how gibberellins works? (3 marks)
1) After imbibition, G is released by the embryo to the aleurone layer 2) G stimulates the aleurone cells to produce hydrolytic enzymes 3) Proteins in the aleurone layer are hydrolysed into amino acids
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Explain how Gibberellin works? (3 marks) FINAL PART
4) Enzyme synthesis from these amino acids occurs to make amylase 5) Amylase diffuses into endosperm and hydrolyses starch 6) These diffuse to embryo for aerobic respiration and growth
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How does gibberelline stimulate the production of proteases?
By triggering transcription and translation in aleurone cells
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Other cards in this set

Card 2

Front

Why are they different the comparison of wind and insect of petals

Back

Because Wind pollinated need wind for it

Card 3

Front

Compare the anther and stigma of insect and wind pollinated flowers

Back

Preview of the front of card 3

Card 4

Front

Outline the structure of a pollen sac?

Back

Preview of the front of card 4

Card 5

Front

Suggest how pollen mother cells are formed?

Back

Preview of the front of card 5
View more cards

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