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21.2 What are the types of reproduction?

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Presentation on theme: "21.2 What are the types of reproduction?"— Presentation transcript:

1 21.2 What are the types of reproduction?
Asexual Sexual involves one parent involves no gametes offspring are genetically the same as the parents usually involves 2 parents involves gametes involves fertilization offspring are genetically different from each of parents

2 21.3 How do organisms reproduce asexually?
Extension 21.3 How do organisms reproduce asexually? Binary fission in bacteria single chromosome parent bacterial cell 1) Chromosome replicates

3 21.3 How do organisms reproduce asexually?
Extension 21.3 How do organisms reproduce asexually? Binary fission in bacteria single chromosome parent bacterial cell 2) Cytoplasm divides into 2 parts

4 21.3 How do organisms reproduce asexually?
Extension 21.3 How do organisms reproduce asexually? Binary fission in bacteria single chromosome parent bacterial cell 3) Two identical daughter cells are formed

5  vegetative parts (e.g. stems, roots & leaves)  new plants
Extension Vegetative propagation in flowering plants  vegetative parts (e.g. stems, roots & leaves)  new plants  allows the plants to survive in poor conditions

6 Vegetative propagation in flowering plants
Extension Vegetative propagation in flowering plants Examples of storage organs : Tuber Bulb Rhizome Corm swollen underground stem e.g. potato   tuber short underground stem with layers of fleshy ‘scale leaves’ e.g. onion bulb horizontally growing underground stem e.g. ginger rhizome short swollen underground stem e.g. Gladiolus corm

7  each bud grows into a new plant  aerial shoots die
Extension Tuber e.g. potato tuber In winter In spring  each bud grows into a new plant  aerial shoots die  new tubers remain dormant

8 In summer  buds use the stored food
Extension In summer Tuber e.g. potato tuber shoot old tuber dries out new tuber formed adventitious roots  buds use the stored food  adventitious roots and shoots develop  new leaves carry out photosynthesis  excess food sent to underground shoots

9  bulb remains dormant under unfavourable conditions
Extension Bulb e.g. onion bulb fleshy scale leaf dry scale leaf bud  bulb remains dormant under unfavourable conditions

10  bud develops into a shoot using stored food  green leaves make food
Extension Bulb e.g. onion bulb new flower stalk fleshy leaf leaf new bulb  bud develops into a shoot using stored food  green leaves make food

11  food is passed from the older parts to the growing regions
Extension Rhizome e.g. ginger rhizome aerial shoot In spring In summer leaf older parts  food is passed from the older parts to the growing regions  food made from photosynthesis is passed down to the underground parts

12  stored food is passed to bud for growth
Extension Corm e.g. Gladiolus corm In spring bud scale leaf remains of last year’s corm  stored food is passed to bud for growth

13  excess food made is passed down to new corm
Extension Corm e.g. Gladiolus corm aerial shoot leaf new corm new corm old corm  excess food made is passed down to new corm  a new corm is developed

14 Artificial vegetative propagation
Extension Artificial vegetative propagation  vegetative propagation carried out artificially  produce desired varieties  e.g. cuttings (插條法) in African violet

15 21.4 How do flowering plants reproduce sexually?
Extension 21.4 How do flowering plants reproduce sexually?  flowering plants reproduce sexually by producing flowers

16 Structure of a flower stigma anther stamen filament style carpel petal
Extension Structure of a flower stigma anther stamen filament style carpel petal ovary ovule nectary sepal receptacle flower stalk sepals, petals, stamens and carpels are attached to this attaches flower to the main stem

17 Structure of a flower Sepals (萼片)
Extension Structure of a flower sepal Sepals (萼片)  the outermost ring (calyx 花萼) of a flower  protect the inner parts of the flower when it is a bud

18 Structure of a flower Petals (花瓣)
Extension Structure of a flower Petals (花瓣) petal  the second ring (corolla 花冠) of a flower  may be brightly coloured to attract insects

19 Structure of a flower Petals (花瓣)
Extension Structure of a flower Petals (花瓣) insect guide petal  may have nectaries to produce nectar which attracts insects  may have insect guides to lead insects towards the nectaries

20 Structure of a flower Stamens (柱頭)  male reproductive organs filament
Extension Structure of a flower Stamens (柱頭)  male reproductive organs filament anther consists of pollen sacs supports anther when anthers ripen pollen sacs split open to release pollen grains anther pollen sacs filament

21 Structure of a flower Carpels (心皮)  female reproductive parts
Extension Structure of a flower stigma (柱頭) style (花柱) Carpels (心皮)  female reproductive parts  the centre of a flower  each consists of style (carries the stigma) stigma (receives pollen grains) ovary (with ovules inside)

22 Structure of a flower Carpels (心皮) ovule stigma style ovary wall
Extension Structure of a flower Carpels (心皮) stigma style ovary wall integuments female gamete ovary ovule micropyle

23 Brief Revision ~ Word corner ~ Carpel ** Carp-  Fruit

24 Structure of a flower Flowers Bisexual (兩性) Unisexual (單性)
Extension Structure of a flower Flowers Bisexual (兩性) Unisexual (單性)  have both stamens and carpels in one flower  have either stamens or carpels in one flower

25 Pollination  transfer of pollen grains from anthers to stigmas
Extension Pollination  transfer of pollen grains from anthers to stigmas male gametes fertilize the ovules Pollination (傳粉作用) insect-pollination wind-pollination

26 The flowers are structurally adapted to pollination.
Extension Wind-pollinated flowers - pollinated by wind The flowers are structurally adapted to pollination. Insect-pollinated flowers - pollinated by insects

27 Insect-pollinated flowers
Extension Insect-pollinated flowers scent Petal nectaries large brightly coloured

28 pollen grains stick onto the leg of the bee
Extension Insect-pollinated flowers scent Pollen grain nectaries small in number rough and sticky/ with hooks large and heavy pollen grains stick onto the leg of the bee

29 Insect-pollinated flowers
Extension Insect-pollinated flowers scent Stigma nectaries sticky inside the flower firmly attached to style

30 Insect-pollinated flowers
Extension Insect-pollinated flowers scent Anther nectaries inside the flower where insects will brush against it firmly attached to filament

31 Wind-pollinated flowers
Extension Wind-pollinated flowers scent Petal nectaries small green or dull-coloured

32 Wind-pollinated flowers
Extension Wind-pollinated flowers scent Pollen grain nectaries large in number smooth and dry small and light

33 Wind-pollinated flowers
Extension Wind-pollinated flowers scent Stigma nectaries large and feathery hand outside the flower for picking up pollen grains from air loosely attached to the style

34 Wind-pollinated flowers
Extension Wind-pollinated flowers scent Anther nectaries hangs outside the flower, exposed to wind loosely attached to filament so that light wind can shake it

35 The growth of pollen tube and fertilization
Extension Fertilization Pollen grains land on the stigma of the same species. style flower stalk sepal The growth of pollen tube and fertilization

36 The growth of pollen tube and fertilization
Extension Fertilization Sugary solution at the tip of the stigma stimulates the pollen grain to develop a pollen tube. style flower stalk sepal The growth of pollen tube and fertilization

37 The growth of pollen tube and fertilization
Extension Fertilization Pollen tube grows down the style and eventually into the ovary by secreting enzymes to digest tissues of the style. style The male gamete moves towards the ovule. male gamete flower stalk sepal The growth of pollen tube and fertilization

38 The growth of pollen tube and fertilization
Extension Fertilization Pollen tube grows through the micropyle. The tip of the tube bursts to release the male gamete into the ovule. style ovule male gamete ovary flower stalk sepal micropyle The growth of pollen tube and fertilization

39 The growth of pollen tube and fertilization
Extension Fertilization Male gamete fuses with female gamete to form a zygote. style ovule male gamete ovary flower stalk sepal micropyle The growth of pollen tube and fertilization

40 Fate of floral parts after fertilization
Extension Fate of floral parts after fertilization wither and drop off remains of stigma and style scar stamen sepal integument seed coat petal ovary wall fruit wall ovule seed ovum embryo A Bauhinia flower after fertilization Fruit (pod) splits open to two halves

41 Fate of floral parts after fertilization
Extension Fate of floral parts after fertilization Fruit consists of protects helps fruit wall seed dispersal made up of seed coat protects embryo provides food food store

42 Structure of a mung bean
Extension Structure of a mung bean Micropyle (珠孔) a hole through which embryo absorbs water Hilum (種臍) a scar; formed when the ovule breaks from the ovary wall Seed coat (種皮) protects the embryo from damage and against attack of micro-organisms External appearance

43 Structure of a mung bean
Extension Structure of a mung bean Plumule (胚芽) Cotyledons (子葉) develops into shoot as food stores provide food for plumule and radicle to develop Radicle (胚根) develops into root Embryo (胚胎) Seed cut opened

44 1 offspring are genetically different from the parents
Extension Advantages and disadvantages of sexual reproduction in flowering plants Advantages 1 offspring are genetically different from the parents  variations (變異) to adapt the environment 2 avoid overcrowding and competition 3 avoid transmission of diseases

45 1 slow way to produce new plants
Extension Advantages and disadvantages of sexual reproduction in flowering plants Disadvantages 1 slow way to produce new plants 2 external agents are needed for pollination


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