BIOL 152 1st Edition Lecture 9Outline of Last Lecturea. Vasculature i. Xylem ii. Phloem II. Angiosperm Reproduction Outline of Current LectureIII. Angiosperm Reproduction contd. & Plant Growth a. Alternation of Generations b. Angiosperm Lifestyle c. Double Fertilization IV. Introduction to Animal PhysiologyV. Three Trends in the Animal BodyPlan a. Symmetry Current LectureAngiosperm Reproduction & Plant Growth**Clicker Question**In some taxa of plant there are two different free living organisms as part ofthis life cycle (alternation of generation) Which of these is 1n?A. Gametophyte (G) B. Sporophyte (S) • A is 1n (sperm and egg), sporophytes are 2nAlternation of Generations• There is a sporophyte generation (2n) • There is a gametophyte generation (1n)• Each can function as different organisms, one make sperm and egg cells,one makes spores• In angiosperms and conifers, the gametophytes are very reduced (stillmulticellular)• In most animal, the sperm and egg are one cell.Angiosperm Lifestyle• In the flowering plants the gametophyte is not free-living 1. Mesioiss in the flower creates pollen and ovule 2n —>1nlittle dots inside are the pollen (or male G)1. Pollen released & must be transfered to female G ( 2. pollen lands on stigma and grows down) — to fertilize ovule 3. Double fertilization — the sperm nuclei fuzes with the egg nuclei (1nfrom sperm, 1n from egg makes embryo a 2n organism) 4. Embryo plus endosperm become a seed — becomes a plant 1. the embryo in the seed is 2n 2. the G doesn’t come from a seed, it comes from a spore, sowhy it’s 1n 1. a fern doesn’t have seeds it has spores **Clicker Question**• Almost any cell in a plant is totipotent, but there are notable exceptions.Which of the following is not totipotent? A. Leaf cell B. root cell C. embryo cell D. pollen • Answer = D (pollen) because it is 1n • the point of this question was to make you think about which cellswere 1n and which were 2n• a leaf cell is 2n, it can become anything because it has 2 copies of thegenome • all the plant species that are 2n have this capacity (to be grown fromleaf cells, root cells, etc)• embryo could because it is egg + sperm• the seed is not just the embryo there is more to a seed than thatthough (see further down) Double Fertilization• the seed is a product of double fertilization • there are 2 sperm nuclei in the pollen (two 1n nuclei) • one of those nuclei fuses with the egg cell to become an embryo (whichis 2n) • the other nuclei fuses with two other cells (2 nuclei) — this makes atriploid nucleus (3n nuclei) • it has 3 copies of the genome • this creates the endosperm • so double fertilization leads to the creation of the embryo and endosperm The seed is made up of the:• seed coat (maternally derived, not coming from fertilization) — at the“top” of the seed and is 2n • it is the brown covering that cracks and goes away as the plant grows • in the middle is the endosperm (3n) • at the bottom is the embryo (2n) • the embryo is the part that becomes the plant, and the endosperm is thenused up by the plant (consumed) • by the time the seed is germinated, the endosperm is gone Endosperm :• Starch, rice/wheat • protein like beans • sometimes very fatty (canola) • the reason it is 3n is so that it can produce many of these biologicalmolecules (carbs, proteins, fats), which can then feed the embryo• endosperm = little packet of food for embryo • advantage to being 3n is that it provides more copies ofeach gene **Clicker Question**• Should the endosperm be totipotent? NO • Think about: how many copies of each chromosome does the planthave? 2 copies (embryo turns into the plant and is 2n) • The endosperm has too many copies to easily turn into any part of theplant — if the endosperm was 2n, then it would be totipotent • Being 3n causes it to be infertile, because it arises from thenuclei making proteins, starches and fats What is a seed and what is a fruit?• A seed is the embryo • a fruit is maternally derived, it is the swollen ovary aroundthe seed **Clicker Question** • Where does meiosis occur? — Use the diagram from the lecture slides • Think about where fertilization happens — have an embryo at D (2n) butmeiosis is before that, or where the 1n’s are being made/split so where is that on the diagram?Answer = A**Clicker Question**The female gametophyte in maize is what?A. 2n B. The green organism at right C. the silkD. the pollen E. the un-polinated kernels on the cob • the gametophyte needs to be where the seed is/going to be, so when youplant the corn, what do you plant? the kernel • Answer = E. The pollen lands on the silks and the pollen tube will grow the full length of that silk and every single kernel must be pollinated in order to get a nice corn on the cob. It grows extraordinarily fast (pollen tubes are the fastest growing cells) Introduction to Animal PhysiologyDefineWhat are animals?- multicellular - sexually reproductive (with some notable exceptions) - complex organ systems - eukaryotic - heterotrophs - mobile (common, not in all) - no cell wall Generalized characteristics of animals (there are 2 major exceptions)- Heterotrophic - euk - multicell - lack cell wall - development is governed by a unique conserved genetic network (hox genes) *see the rest on slides*exceptions = the sea slug, which eats algae then digests the cell wall and brings the chloroplasts into its body so it can photosynthesize-sponges (porifera) who have no true muscles, nerves or box genesThree Trends in the Animal “Body Plan”Symmetry:- radial symmetry: can split it laterally and has symmetrical sections- bilateral symmetry: they must have a clearly defined front, back, top andbottom - only animals that lack this are the cnidaria and upwards - ancestral traits - one that is shared by the taxa (groups of organisms) and includesancestors - for example, in the group mammals, giving birth to live young is anancestral trait (going back in time all mammals have this) - derived traits - one not shared by ancestors but present in decedents - walking around on two feet is a derived trait for humans **Clicker Question**Does a starfish have radial or bilateral symmetry?Radial.Is radial symmetry a derived or an ancestral trait?Derived.The ancestral