R2101 2.1 & 2.3 Structure of Plant cell & Roots Flashcards
Features and functions of nucleus?
Controls functions of the cell and contains DNA; DNA can replicate itself for cell division
Where does cell division and growth occur in plants?
Growing points or meristems
- apical meristem (tip of bud, root)
- lateral meristem = axillary bud
How do plants increase in size?
1. Primary growth: meristematic tissue in the apical and lateral meristems of the stems and roots divides
2. Expansion (or elongation)
3. Differentiation (?)
Describe cell division.
- duplication of the genetic material and its equal distribution to each of two ‘daughter’ cells
- usually preceded by cell growth, so that when the cell divides, the two daughter cells are essentially similar to the parent cell
- in mitosis the daughter cell ends up with exactly the same number of chromosomes as the parent cell
- takes place when an organism grows, replaces old cells or reproduces asexually
Describe cell expansion.
As new cells are formed, older ones expand.
At first the cell is full of cytoplasm with the nucleus in the middle.
Several vacuoles come together to form the large, sap-filled vacuole.
Expansion takes place by uptake of water (by osmosis) into the developing vacuole.
The shape depends on how elastic the cell wall is, which is influenced by how cellulose is laid down.
Difference between woody and herbaceous stem?
3 different stem structures:
- herbaceous dicot stems which have discrete vascular bundles arranged in cylinder appearing in narrow rings
- woody dicot stems which have vascular bundles in ring
- monocot stems which have scattered vascular bundles.
http://www.bio.miami.edu/dana/dox/stem.html
Where does each of the following take place:
i) photosynthesis
ii) control of cell turgor
iii) up-take (absorption) of minerals
iv) aerobic respiration
i) chloroplast
ii) vacuole
iii) cell membrane
iv) mitochondrion
Name a plant tissue where cell division takes place.
apical meristem
vascular cambium
Describe the process which causes plant cells to expand.
Water passes into the cell by osmosis.
As water enters, turgor pressure inside the cell presses outwards against the cell membrane and stretches it and therefore expands the cell.
Describe osmosis.
Diffusion of water molecules from a dilute solution (high concentration of water) to a more concentrated solution (low concentration of water) across a selectively permeable membrane
Name the cell component that carries out the following functions:
i) limits cell expansion
ii) water storage
iii) suspends cell organelles
i) cell wall
ii) vacuole
iii) cytoplasm
Functions of cell membrane?
Controls the movement of substances in and out of the cell.
Functions of vacuole?
Controls cell turgor/stores waste products and water.
Functions of cell wall?
Controls the shape of the cell/limits cell expansion
Strengthens the cell and supports the plant
Functions of chloroplast?
Site of photosynthesis/site of chlorophyll synthesis
Functions of nucleus?
Contains genetic information so controls cell processes