Sexual Reproduction - Flowering Plant Flashcards
Suggest two ways by which pollen lands on stigma
Wind
Animal
By what process does the pollen give rise to the sperm nuclei
Mitosis
What is the fate of the sperm nuclei?
i) fuses with egg to form diploid zygote
ii) fuses with two polar nuclei to form triploid endosperm nucleus
What does the ovule develop into after fertilisation?
Seed
Explain what is meant by the term dormancy in seeds
Resting period when seeds undergo no growth and have reduced cell activity / metabolism despite presence of favourable conditions
How does digestion contribute to successful seed germination?
Make food soluble
Digestive activity during seed germination -
What Agar plates did you use for this investigation?
Starch agar plates
Digestive activity during seed germination -
Name a type of enzyme that carries out this digestion
Amylase
Digestive activity during seed germination -
Why were the seeds soaked in water at the start of the investigation?
To enable metabolic activity
Soften testa
Digestive activity during seed germination -
Why is it recommended you sterilise the seeds?
To kill all micro organisms
Digestive activity during seed germination -
Why were the split seeds placed open-side down on the agar?
Enzyme is exposed to substrate
Digestive activity during seed germination -
How do you know that digestive activity had occurred on one of your investigation plates?
When add iodine, agar around plates in dish with unboiled seeds will stay clear
Digestive activity during seed germination -
How did you know that digestive activity had NOT occurred on one of your investigation plates
When iodine was added, there will be no clear areas around seed instead, will be blue-black
Digestive activity during seed germination -
Give one reason why digestive activity did not occur in one of your investigation plates
Enzymes were denatured in boiling
What types of cell division occur during production of the female gametes in flowering plants
Meiosis, Mitosis
What types of cell division occur during production of the male gametes in flowering plants
Meiosis, Mitosis
Give the precise location of the production of the female gametes
Embryo sac
Give the precise location of the production of the male gametes in flowering plants / give the site of production of pollen grain
Anther
Give the precise location of fertilisation under normal circumstances
Embryo sac
Name the next stage of development following formation of zygote
Embryo
Give an advantage and disadvantage of sexual reproduction in organisms
Advantage - inc variation
Disadvantage - requires two parents [diff finding mate], more complex [takes longer]
Following fertilisation, from precisely which part of the flower is the seed formed?
Ovule
What is meant by the term monocotyledonous
Has one cotyledon - one seed leaf
Name two biomolecules stored in endosperm or cotyledon tissue
Lipids, Proteins
Give one way knowledge of seed dormancy has been useful to humans - horticulturists and farmers
Maximise growing season
Dormancy - means it can withstand harsh conditions
Graph - 2015
Suggest why the measurement of dry mass is preferred in these investigations??
Water content can vary between seeds
Graph - 2015
Explain why the dry mass of the endosperm tissue decreases?
Food transferred to embryo
What process begins when dry mass of embryo shoots up
Photosynthesis
Graph - 2015
Would you expect the total dry mass of the seed [embyro + endosperm] to have remained the same up until photosynthesis occurred?
No, will lose mass due to respiration
Describe in detail the events that follow the arrival of a pollen grain to the stigma, up to and including fertilisation
- pollen grain lands on stigma and germinates forming a pollen tube which grows down through style to opening of embryo sac
- the tube nucleus at the tip of the pollen tube disintegrates and the generative nucleus divides by mitosis in the tube to form two male gametes
- one of the male gametes fertilises the egg to form a diploid zygote [which after develops into an embryo]
- other male gametes and the polar nuclei fuse which results in triploid endosperm
Identify the structure on which the pollen grain must land to complete pollination
Stigma
Name two methods of cross pollination
Wind
Animal
Many species of plant have mechanisms that prevent self-pollination. Suggest how such plants could benefit from this
Greater variation
Which part of the flower usually develops into a fruit
Ovary
Function of petal
Attracts insects for pollination
Function of anther
Where pollen grain is produced that produces male gametes
Function of stigma
Where pollen grain lands
Function of stamen
Makes Male gamete
Function of carpel
Makes female gamete
Function of sepal
Protects the bud
Function of receptacle
Forms base of flower
What are gametes?
Haploid cells capable of fusion
Function of style
Through which the pollen tube grows
Function of ovary
Holds ovule
Function of ovule
Holds egg
Function of filament
Supports anther
Function of anther
Makes male gamete
Name one structure through which the pollen tube grows in order to reach embryo
Style
What type of division takes place when the generative nucleus divides to form two male gametes and explain your answer
Mitosis
Two daughter cells are produced
Chromosome number retained
What does each male gamete fuse with in the embyro sac and what’s the product
Egg - diploid zygote
Polar nuclei - triploid endosperm
As seed forms following fertilisation, a good store develops in one of the two structures. Name any one of these structures
Endosperm
Cotyledon
Describe the development of pollen grains from microspore mother cells
- each pollen sac has a layer of diploid cells called microspore mother cells which divide by meiosis to produce four haploid microspores
- each microspore nucleus divides by mitosis to produce a generative nucleus and a tube nucleus
What is meant by the term fertilisation?
Fusion of male and female gametes to form a diploid zygote
Give a brief account of the process of fertilisation in flowering plants
- the generative nucleus divides by mitosis in the tube to form two male gametes
- one of the male gametes fertilises the egg to form diploid zygote
- other male gamete fuses with two polar nuclei to form triploid endosperm
Give two ways in which the dormancy of seeds is of benefit to plants / advantages
Gives time for embryo to develop
Survival during unfavourable conditions
Increased dispersal
In the case of water, oxygen and a suitable temperature, describe its effect on the process of germination
Water - for enzyme action
Temperature - needed for enzyme activity [optimum temp]
O2 - needed for respiration
Which part of the embryo in a germinating seed gives rise to the root
Radicle
Which part of the embryo in a germinating seed gives rise to the shoot
Plumule
What is meant by germination?
Regrowth of an embryo into a new plant
What is an agar plate?
Petri dish containing a jelly medium
Experiment of digestive activity -
An extra food material is added to the agar plate for this demonstration, give an example
Starch
Experiment of digestive activity -
Outline the procedures that you carried out in setting up this demonstration
- soak seeds and split in half with backed blade
- kill two seeds by boiling them [act as control]
- sterilise seeds by soaking in alcohol for 10 mins
- wash off alcohol with water
- flame forceps with bunsen burner and allow to cool [sterlises it]
- with forceps place seeds fade down on starch agar plates
- place covered dishes in warm place for two days
Experiment of digestive activity -
What control did you use for this demonstration?
Boiled seeds
Experiment of digestive activity -
What procedure did you carry out in order to show that digestive activity had taken place
- remove half seeds and add dilute iodine solution [test for starch]
- after 2 mins, pour off iodine
Experiment of digestive activity -
Describe results you obtained in the experimental plate and the control plate
Experimental plate - clear around seeds, no blue black
Control plate - blue/black around seeds
Features / adaptions of wind pollinated plants
Petals - small, green, no scent/nectar
Pollen- huge amounts, small + light
Anther- large, outside petals
Stigmas- large and feathery, out petals
Give an example of a wind pollinated plant
Grasses, oak
Features / adaptations of insect pollinated flowers
Petals -rage, coloured, scented/nectar
Pollen - smaller amounts, large and sticky
Anthers - smaller, inside petals
Stigmas - smaller, rounded and inside petals
Give an example of an insect pollinated plant
Daisies, dandelions and buttercups
State two locations in the seed where food may be stored
Cotyledon, Endospore
The embryo plant within the seed has a number of parts. List two of these parts, apart from the food stores and give a role for each of them
Radicle - develops root
Plumule - develops shoot
Give the term by which fruit without seeds are formed
Parthenocarpy
State one method that is used to produce seedless fruits
Growth regulator [auxin]
Digestive activity during seed germination -
What substrate did you use for digestive enzymes?
Starch agar
Describe the role in the process of germination of two of the factors or a seed to germinate
Water - for enzyme action
Oxygen - needed for aerobic respiration
Temperature - optimum temperature for enzyme activity
Describe germination
- seed absorbs h2O and O2 and the enzymes digest the food stored in cotyledons or endosperm
- nutrients are moved to the growing embyro and used in respiration for formation of new cells
- radicle forms the root and plumule forms the shoot
- leaves formed and photosynthesis begins
