Download Angiosperm Review Sheet

Angiosperm Anatomy​
­ structures & their functions Vegetative (Non­reproductive) Plant Body: Roots​
: A complex branching network that grows in between soil particles. They attach the plant to the ground and holds it upright, preventing it from getting knocked over by wind or rain. Roots absorb water and dissolved nutrients from moist soil. Stems:​
The stalk­like structure of a plant that holds its leaves up to the sun so it can go through photosynthesis for food. It’s beneficial to have a tall, yet sturdy, stem to compete with other plants for solar energy. Leaves: ​
Structures that capture the sun’s energy. Organs inside them convert sunlight into energy the plant can use. Leaves have a waxy coating called the ​
cuticle​
that protects leaves from losing water to dry air. Tissue Systems: Vascular Tissue​
: System in taller plants where water and nutrients are transported throughout the plant. ­> ​
Xylem ​
­ Carries water and nutrients from roots ​
up​
to the stems and leaves ­> ​
Phloem ​
­ Carries products of photosynthesis (sugar, etc) to various parts of the plant, traveling ​
up & down​
. The Flower (Reproductive Structures): Stamen:​
A flower’s ​
male​
organ composed of the anther and filament. The main function of the stamen is to produce ​
pollen grains​
that contain male gametes (sperm cells) for reproduction. The pollen grain is important because it can be carried by wind or animals since the sperm doesn’t have flagella to swim, being on land. ­> ​
Anthers​
­ the organs that produce pollen ­> ​
Filament ​
­ long thin stalks that attach to the base of a flower and support the anthers. Carpel​
: A flower’s ​
female​
organ composed of the stigma, style and ovary (Also referred to as pistil). It sticks out above the stamen so that pollinators can easily transfer pollen and fertilize the seeds. ­> ​
Stigma ​
­ sticky tip that receives pollen ­> ​
Style​
­ long stalk that connects the stigma and ovary. It is where pollen tubes deliver sperm cells to the egg during reproduction. ­> ​
Ovary​
­ contains ​
ovules​
which develop into seeds during fertilization. The ovules are where female gametes (egg cells) are produced. The seed acts as a protective casing for the embryo and allows the plant to develop without danger of drying out. The ovary can develop into a fruit when mature. Petals​
­ Modified leaves that use their scent, colour and shape to attract pollinators. Sepal​
­ Leaf­like structures that grow out from the top of the stem. They protect the flower while the flower is developing from a bud. Receptacle​
Base of the flower where it attaches to the stem. Its job is to keep all the flower’s parts together and keep the flower in an elevated position so it attracts pollinators. Reproductive Cycle: Pollen development: In the anther there are cells called microsporocytes (2n). These cells undergo meiosis to become microspores (n). From there they go through mitosis to become microgametophytes (n) which is pollen with 2 non­flagellated sperm. Egg development: In the ovules there is a cell called the megasporocyte (2n). It goes through meiosis to create four haploid cells (n), but only one of them will survive. The cell that survives is called a megaspore (n) and it will go through mitosis three times to create 8 cells. Two of them will fuse together to form the central cell (2n) so we now have 7 cells. One of these cells is the female egg. This structure is called the megagametophyte, also known as the embryo sac. Pollination & Fertilization: Abiotic and biotic factors like wind or pollinators carry pollen to the stigma. A pollen tube is created down the style when a pollen grain reaches it. The 2 sperm cells from the pollen travel down the tube to reach the embryo sac in the ovule. One of the sperm fuses with the egg (n) to create a zygote (2n) and the other sperm fuses with the central cell (2n) to create an endosperm (3n). This is a process unique to angiosperms called double fertilization. The endosperm is a food source for the zygote. Seed Formation: The zygote develops into an embryo and starts to mature. The ovule detaches from the wall of the ovary and the ovule’s outer cell layers harden to form a seed coat for the embryo. At this point, the ovule has become the seed. Fruit Development: The ovary swells and flower parts (petals) start to fall off. The ovary then continues to grow into the fruit. The function of the fruit is to help protect and disperse the seed, whether it be getting caught by the wind, getting eaten by an animal, etc. When the seed is released from the fruit it can begin germination where it eventually develops into the mature angiosperm plant that we begun with and the cycle is repeated.