-
Fragmentation
Can be an artificial process (cuttings) or natural process
-
Runners
horizontal stems that can lead to completely new plants
-
Asexual reproduction
natural cloning where all the offspring are genetically identical to the parent plant
-
Sexual Reproduction
produces offspring combine the genes from 2 parents and are genetically different from their parents
-
Sporophyte
diploid plant which produces haploid spores
-
gametophyte
- haploid plant which produces gametes
- In mosses and fern, they are small and independent
-
What is essential for sexual reproduction?
Water
-
In gymnosperms and angiosperms (seeded plants) - what about gametophyte and sporophyte?
The gametophyte is very small and relies on the sporophyte and it is a par of the sporophyte.
-
2 types of spores in flowering plants
- Hetersporous
- Megaspores - gives rise to the female gametophyte
- Microspores - gives rise to the male gametophyte
-
Female gametophyte
embryo sac containing an egg cell
-
male gametophyte
a pollen grain (sperm)
-
zygote
develops into the seed, which will form into a new sporophyte
-
Stamens
male reproductive part and consist of the filaments (stalk) which hold the anther
-
Anther
contains the pollen grains (male gametophyte)
-
Carpel
- female reproductive part
- vase shaped structure made up of the stigma, the style, and the ovary
-
Stigma
- at the top of the carpel
- sticky structure designed to catch the pollen
-
Style
- the neck of the carpel
- pollen must "grow" through the style to reach egg
-
Ovary
- at the bottom of the carpel
- contains the ovules which become seeds and the outer layers of the ovary becomes the fruit
-
incomplete flowers
lack one or more of the 4 floral parts
-
Microspores (mother cells)
develops inside the pollen sac
-
Integument
- outer layer of ovule
- tissue is diploid
-
formation of female gametophyte
- 1) megaspore mother cell develops within the ovule
- 2) megaspores divides by meiosis to form 4 haploid megaspore
- 3) 3 of the 4 megaspores degrade
- 4) the remaining one of the 4 goes through 3 rounds of mitosis but not cytokinesis which results in 8 nuclei in one cell
- 5) the nuclei are distributed 3 on each en of the megaspore and 2 in the center.
- 6) cytokinesis occurs forming 7 cells
- 3 cells on each end of the embryo sac (one is the egg)
- one larger central cell with 2 polar nuclei
-
Primary endosperm cell
larger center cell
-
Pollination
- starts when pollen from an anther lands on a stigma
- pollen grain grow a tube down through the style towards the ovary
- 2 sperm cells from the generative cell move down the tube to teh ovary where a double fertilization occurs
-
Double Fertilization
- one sperm fuses with the egg cell to form the zygote
- the other sperm fuses with the polar nuclei in the primary endosperm cell making this triploid endosperm (3 set of chromosomes) tissues
-
3 parts of embryo
- hypocotyl
- epicotyl
- cotyledons
-
Dicots embryo parts
Monocots embryo parts
- 2 cotyledons in the embryo
- 1 cotyledon
-
Coleoptile
a tough sheath that protects the cotyledon in monocots
-
Wind pollinated flowers
- inconspicuous and unscented
- produces LOTS of pollen because of it low probability of a hit for an individual pollen grain (oaks and maples)
-
Animal pollinated flowers
- attract animal pollinators
- frustrate undesirable visitors
- ensure cross-fertilization
-
4 types of dispersal
- wind dispersal
- mechanical dispersal
- water dispersal
- animal dispersal
-
What are the stimuli that plants receive from their environment?
- Direction of gravity
- Direction, intensity, and duration of sunlight
- Strength of the wind
-
Phototropism
- the bending of plants towards sunlight
- first plant respond discovered and the studied by Charles and Francis Darwin.
-
Darwins experiments
- region below the tip of grass coleoptile bends towars light
- covering the tip with an (dark) opaque cap stops the bending
- covering the bending region does not stop the bending
-
Peter Boysen-Jensen
- discovered the mechanism of the bending
- tip cut off, elongation and bending is stopped
- tip is replaced, elongation and bending is restored
- if a porous gelatin slab is between the severed tip and shoot, elongation and bending is restored
- If the tip of the plant was
- cut off, then the elongation and bending is stopped.
- If the tip of the
- coleoptile was replaced, then the elongation and bending is restored.
- If the replaced tip of the
- coleoptiles had a porous gelatin slab between the severed tip and shoot, then
- the elongation and bending is restored.
- If the replaced the tip of the coleoptiles had a thin layer of non-porous
- mica between the severed tip and shoot, then the response to light remained
- blocked
- If the tip of the plant was
- cut off, then the elongation and bending is stopped.
- If the tip of the
- coleoptile was replaced, then the elongation and bending is restored.
- If the replaced tip of the
- coleoptiles had a porous gelatin slab between the severed tip and shoot, then
- the elongation and bending is restored.
- If the replaced the tip of the coleoptiles had a thin layer of non-porous
- mica between the severed tip and shoot, then the response to light remained
- blocked
-
Hormones
chemicals produced in one location and transported to other regions where they exert specific effects
-
Abscisic Acid
- inhibitory hormone
- causes stomata to close when water scarce
- maintains dormancy in buds and seeds in bad weather by inhibiting the action other hormones especially gibberellin
-
Auxins
- regulate plant responses to light (phototropism) and gravity (geotropism)
- promote cell elongation in shoots
- prevent growth of lateral buds
- in roots : low concentrations stimulate elongation, higher concentrations inhibit elongation, stimulate root branching
- stimulate fruit development
-
Statoliths
mediated the bending due to gravity
-
Gibberellins
- promote cell elongation in stems
- stimulate flowering, fruit development, seed germination, and bud growth
-
Cytokinins
- promote cell division including lateral meristems
- stimulate overall metabolism, delaying the aging of leaves
-
Ethylene
- gaseous hormone
- causes fruit to ripen
- causes breakdown of cell walls in abscission layers: allowing leaves fruit and flowers to drop off at appropriate times
-
Homeostatsis
tendency of life to try and maintain the structure and regulate the internal environment
-
Negative feedback
a change in one direction causes a series of events in the other direction to counteract the change
-
3 components of negative feedback
- set point - hypothalamus
- sensors - points throughout body
- effectors - shivering, faster metabolism, restrict blood to body's surface
-
Positive feedback
initial change in one direction sets off a series of events that intensifies a change in that same direction
-
Tissue
- composed of cells with similar structure and function or non-cellular components made by the cells (bone and cartilage)
- Epitelial
- connective
- Muscle
- Nerve
-
Epithelial Tissue
- cells form continuous sheets called membranesforms a barrier because it has no blood vessels
- nourished by diffusion from capillaries beneath it or is continuously lost and replaced by cell division
-
Exocrine glands
- glands remain connected to epithelial tissue and secrete material either outside that body or into a cavity
- salivary, sweat, and sebaceous glands
-
Endocrine glands
glands have lost their connection to the epithelial tissue and secrete material into the bloodstream
-
Connective tissue
- includes the layer beneath the skin called the dermis, tendons, ligaments, cartilage, bone, fat, blood and lymph
- surrounded by large quantities of extracellular substances that are secreted from the connective tissue
-
Dermis
responsible for nourishing the epithelial via capillaries and fluid-filled spaces
-
Tendons and ligaments
contain densely packed collagen fibers in a parallel arrangement
-
Cartilage
- covers ends of bones at joints
- supports respiratory passages
- supports ear and nose
- forms shock-absorbing pads between vertebrae
-
bone
resembles cartilage hardened by deposits of calcium phosphate
-
Fat cells (adipose tissue)
specially modified to act as storage sacs for triglycerides
-
Muscle tissue
- specialized for contraction
- made up of cells that contain actin and myosin filaments proteins
-
3 types of muscle
- skeletal (straited)
- smooth
- cardiac
-
Nerve tissue
composed of neurons (specialized to generate and conduct electrical signals)
-
4 parts of neurons
- dendrites - receive signals
- cell body - maintains and repairs the cell
- axon - conducts electrical signal to target cell
- synaptic terminals - transmits the signal to target cell at a region call the synapse
|
|