d3.1 (reproduction) Flashcards
parts of a plant’s reproductive system & functions x9
Sepal: Protects developing flower inside bud
Petal: Colourful, attracts pollinators
Anther: Produces pollen
Pollen: Contains male nuclei for fertilization
Filament: Stalk that holds up anther
Stigma: Sticky part of carpel, where pollen lands
Style: Part of carpel that supports Stigma
Ovary: Base of carpel, contains ovule. Sometimes a fruit.
Ovule: Chamber within ovule where female nuclei develops
hermaphroditic definition
contain both male and female structures
key features of insect-pollinated flowers x5
bright colours
sweeter scent
sugary nectar
visible landing platforms
sticky pollen
pine trees produce two types of cones: male cones and female cones. male cones are smaller and produce pollen, while female cones are larger and contain seeds.
how have some species of conifer cones adapted to avoid self-pollination?
female cones grow on higher branches, and male cones on lower branches. this is thought to prevent self-pollination as the wind will carry pollen from male cones away from drop site.
define heterostyly. how do primrose flowers exhibit this?
where there are different floral forms within the same species to facilitate cross-pollination
pin eyed: style is long, and the stigma is positioned farther out in the flower. anthers are closer to the base of the flower. pollen is positioned lower down in the flower
thrum: style is shorter, and the stigma is positioned closer to the base of the flower. anthers are located nearer to the top of the flower. pollen is placed higher up.
this encourages cross pollination within the species
define dioecious plants (give 2 examples)
plants that have separate male and female plants (i.e. willows & cannabis)
incompatibility mechanisms present in some plants aims to reduce self-pollination. what are 4 examples of this?
pollen grain lands on stigma, fails to grow pollen tube
pollen grain grows pollen tube, but it doesn’t enter style
pollen tube grows and enters ovule, but pollen nuclei degenerate before fertilization
fertilization occurs but plant embryo degenerates
what is gametophytic self-incompatibility (GSI) mechanism (how does it work)?
the pollen grain itself carries the self-incompatibility (SI) allele, and the pollen is rejected if it shares the same allele as the pistil (female part of the flower)
how is sporophytic self-incompatibility (SSI) different from gametophytic self-incompatibility (GSI)?
self-incompatibility is determined by the alleles in the pollen parent’s tissues (sporophyte), rather than in the pollen itself
(stigma identifies the incompatibility based on the pollen’s genetic makeup, not the allele carried by the pollen grain itself, if the pollen grain has one or more of the same alleles as the pistil, the pollen will be rejected)
example species of gametophytic self-incompatibility (GSI) and sporophytic self-incompatibility (SSI) (1 each)
GSI = brassica
SSI = roses
what is hybrid self-incompatibility (HSI)? when can it be observed?
a combination of both GSI and SSI mechanisms, often found in hybrid species. it prevents self-pollination in hybrids
5 ways of seed travel
wind, animals, water, bursting, humans
what is the point of a seed going dormant?
allows seeds to wait until environmental conditions are favourable
define imbibition, what does it do?
process of seed absorbing water. activates biochemical processes in seed
define radicle (in relation to seed growth)
first plant structure to grow, turns into the root
define hypocotyl
first above ground structure
where is meristem tissue found? what is it the site of?
present at tips of roots and shoots. it is where plant growth occurs
at fertilization, two ______ _________ fuse to form a _______ __________
haploid gametes, diploid zygote
to maintain the correct number of chromosomes in each generation, there must be a reduction in the number of chromosomes in the forming of eggs and sperm– why?
by uniting two gametes with half the number of chromosomes, the full chromosome number is restored each generation
define gametogenesis
the process of the production of gametes
4 general steps of gametogenesis
mitosis of germ cells to create a supply of cells that can divide to become gametes
growth of the germ cell prior to dividing to ensure it has the materials and nutrients it will need for division
two divisions of meiosis to create four haploid daughter cells.
differentiation of the haploid daughter cells to create specialized gametes (oocytes or spermatozoa)
what is a germ cell?
stem cells within the gonads (testes or ovaries) that can divide and differentiate to become gametes (a cell that develops into a reproductive cell)
testes are composed largely of seminiferous tubules (coiled tubes). what do the walls contain?
cells that produce sperm
spermatogenesis cell names for each step x5
spermatogonia
primary spermatocytes
secondary spermatocytes
spermatid
spermatozoa