No Marking Criteria Marks
(a) Diagram shows the germination of pollen tube towards the embryo sac in flowering plants
Based on diagram 5.2, explain the fertilization process in embryo sac P1-One male gamete will fuse the egg cell to form a diploid zygote
P2-Another male gamete will fuse with 2 polar nuclei to form triploid nucleus P3-Both process take place at the same time //double fertilization occurs
1 1 1 3
(b) Reproduction in plants involves the fusion of male gamete and female gamete.diagram 4.2 shows a male gamete 4.3 shows the early stage of double fertilization in flowering
Based on the diagram name the structure S
Polen grain 1 1
(c) Explain what happen to structure S when it land on structure T F1-Sucrose solution /sugar on structure T stimulate germination of S F2-Pollen tube grows out the ovary
F3-It grows down (the style) into ovary F4-enter ovule through microphyle
1 1 1 1 3 T
No Marking Criteria Marks (e) Complete diagram 4.4 below to shows how double fertilization occurs
The diagram 4 shows the process of double fertilization in a flowering plants Criteria of the diagram :
Correct drawing with pollen tube enter through the microphyle end -1 Correct drawing of embryo sac with 2 polar nuclei and egg nucleus inside- 1 Correct drawing of pollen tube with 2 male nuclei with correct labels -1
1 1 1 3 (f)
Name the cells contains in Y that involves in double fertilization process
2 polar nuclei//1 egg cell 1 1
(g) How structure W cause the formation of structure X F-W rough sticky wall
E1-(sticky wall)stimulate the germination /elongation of structure X to embryo sac
1 1 2
(h) State the two nuclei found in the structure X
No Marking Criteria Marks (i) Describe briefly the movement of structure X
P1-X secretes enzymes to digest the surrounding tissue as it grows downward
P2-the direction of growth of structure X is controlled by the nucleus tube which at the tip of the structure
1 1 2
(j) Explain why the fertilization process is process is known double fertilization P1-because there are two fertilization
P2-First fertilization happen when one of the male gamete fuses with the egg to form zygote P3-The second fertilization happens when the other male gamete fuses with the two polar nuclei to form a triploid nucleus (3n)/endosperm
1
1 1 3
(k) Explain what happen happens to the structure Y after double fertilization? P1-Nuclues triploid /zygote triploid undergoes mitosis
P2-Then develop to endosperm P3-Zygote develop to embryo
P4-(endosperm) store the food for the development of embryo/seed germination
1 1 1 1 3
Essay enhancement corner
No Marking Criteria Marks
(a) The product form the process in (a) is transferred onto the stigma through pollination Explain the process that will occur in the style and ovary after pollination
P1 On the stigma, sugar stimulates pollen grains to germinate P2 Form pollen tube
P3 Pollen tubes grows into the style and towards the ovule, led by tube nucleus P4 Generative nucleus undergoes mitosis and form two male gamete nuclei P5 Pollen tube penetrates the ovule through micropyle
P6 Tube nucleus disintegrates
P7 One male nuclei fuses with the egg cells to form diploid zygote
P8 Another male nucleus fuses with the two polar nuclei to form triploid zygote P9 This process is known as double fertilization
P10 Triploid nucleus divide to form endosperm (ie nutritive tissues) P11 Diploid zygote divides and grows into embryo
1 1 1 1 1 1 1 1 1 1 1 10
No Marking Criteria Marks (b) Diagram shows the proves of fertilization in flowering plants
Based on diagram describe how this process occurs 10
P1-Pollen grains have been released form the anther to the stigma for pollination by insect to wind
P2-When pollen grain lands on stigma, epidermal cell secrete sucrose solution P3-(sucrose solution) stimulates the pollen grain to germinate and pollen tube P4-the pollen tube grows down the style to ward th ovule
P5-it secretes enzyme to digest surrounding tissues as it grow downward
P6-The generative nucleus (follows behind it) divides by mitosis to form two male gamete nuclei
P7-the male gamete nuclei move down the pollen tube lead by the tube nucleus
P8-when the pollen tube reaches the ovary, it penetrates the ovule through the microphyle P9-The tube nucleus degenerates, leaving a clear passage for the male nuclei to enter the embryo sac
P10-one male gamete fuses with two polar nuclei to form triploid nucleus which divide by mitosis to form endosperm tissue
P12-this fertilization is called double fertilization any 10 point
1 1 1 1 1 1 1 1 1 1 1 10 Mature embryo sac
Ovary Pollen grains
No Marking Criteria Marks (c)
Based on the diagram ,explain how double fertilization occurs in the plant10
P1-Anther produces pollen grains .male gamete
P2-Polen mother cell (in the anther) undergoes meiosis to produce (four) megaspores (n)/haploid cells /tetrad
P3-Megaspores (n)/haploid cells /tetrad develop into pollen grains
P4-The nucleus of each megaspores (n)/haploid cell /divides by mitosis
P5-to form one tube nucleus and one generative nucleus
P6-When a pollen grain falls on the stigma
P7-Stimulates (the pollen grain to germinate to) form pollen tube
P8-(during the growth of pollen tube) the generative nucleus divides mitotically
P9-to produce two male gametes
P10- to the male gametes move/follow behind the tube nucleus (down the pollen tube until they reach the microphyle
P11-The tube nucleus disintegrates and the two male gametes enter the embryo sac
P12-(during double fertilization ), one male gamete fuses with the egg cell/ovum to form a diploid zygote and
P13-The other male gamete fuses with two polar nuclei to form a triploid nucleus (so double fertilization occurs) any 10
1 1 1 1 1 1 1 1 1 1 1 1 10
No Marking Criteria Marks (d) Diagram shows the process of double fertilization in the flowering plant
Describe the process
P1-One of the male nuclei which is x fuses with egg cell nucleus which is D P2-the other form a diploid Zygote
P3-The other male nucleus fuses with two polar nuclei which is C P4-To form nucleus divides to form the endosperm
P5-This triploid nucleus divides to form the endosperm P5-That will provide food to the embryo
1 1 1 1 1 1 4
(e) Diagram 7.2 shows the growing of pollen tube in the style and the process of double fertilization in flowering plant.
Describe the growing process of pollen tube in the style and the process of double fertilization in flowering plant7
Growing of pollen tube process
P1- Sugary/sucrose solution stimulate the growing of pollen tube P2 - pollen tube grows down the style towards the ovule
P3 - The generative nucleus divides to form two male gametes nuclei P4 - Leading the front is the nucleus tube
1 1 1 1 Pollen grains Pollen tube Embyro sac Integumens Sytle Antipodal cell Polar nucleus Egg cell Pollen tube
Double fertilization
P6 - Pollen tube penetrate the micropyle to reach the egg cell P7 - Nucleus tube disintegrate
P8 - one of male nucleus fuses with egg cell to form a diploid zygote
P9 - other male gamete nucleus fuses with the two polar nuclei forming a triploid nucleus. P10 - which later develops into the endosperm
P11 - the synergid cells and the antipodal cells disintegrate Any 7 P 1 1 1 1 1 1 10