6 Plant nutrition Flashcards
Photosythesis
The chemical process by which plants manufacture carbohydrates from raw materials using energy from light.
carbon dioxide + water → glucose + oxygen
6CO2 + 6H2O → C6H12O6 + 6O2
Chlorophyll
Green pigment found in plants, which absorbs energy from sunlight for photosynthesis.
Chloroplast
The site of photosynthesis
Contains chlorophyll to absorb light, and enzymes and structures needed for photosynthesis
Uses and storage of carbohydrates in a plant
As an energy source
For storage: Glucose is a highly reactive molecule and unwanted chemical reactions may happen. Therefore, glucose is converted into sucrose (a more stable molecule) before being transported in the phloem to the different parts of the plant. The sucrose can easily be changed back to glucose as and when needed by the plant.
For structural support: Some glucose is converted to cellulose. Cellulose is an important component of the plant cell walls.
To assist pollination: Glucose is also used to make nectar. Nectar is a sweet, sugary liquid that attracts animals like insects and birds. These animals in turn help with pollination.
Minerals
A group of substances that are essential to organisms in low concentrations to allow them to carry out various functions.
Uses of mineral ions In plants
Plants use magnesium ions for making chlorophyll. There is a magnesium ion at the centre of each chlorophyll molecule, and this is vital for the correct function of chlorophyll.
Phosphate is needed for normal development and timely maturing
Nitrate is needed to make amino acids, chlorophyll and nucleotides
Limiting factor
The variable in the environment that controls the rate, growth or abundance of a biological processes. For instance, temperature can be the limiting factor in the growth of a plant.
Limiting factors in a plant
Water/ions
Light intensity
Chlorophyll
Carbon dioxide
Temperature
Inside the leaf are places where
Carbon dioxide moves in, out and around
Water travels into and around the leaf
Sunlight passes through the leaf
Multiple layers of cells work together to make complex sugars for food
Minerals and water move around the leaf through bundles of tubes.
Leaf adaptations
They have large surface areas, which exposes a larger area to sunlight and air, and helps in the easier absorption of these materials.
They are thin, which ensures that the carbon dioxide from the air diffuses quickly to the photosynthetic cells. The thinness of the leaves also helps the light to penetrate easily.
The leaf consists of
(1) palisade mesophyll
(2) guard cell
(3) xylem and phloem
(4) spongy mesophyll
(5) cuticle and epidermal cells.
Cuticle
The waxy outer layer of a leaf that reduces the water loss through evaporation.
Upper epidermis
The boundary layer in a leaf that protects the leaf whilst still allowing light and gases into the lower layers.
Palisade mesophyll layer
Tissue in which photosynthesis happens
Box-shaped cells that pack closely together; each cell has lots of chloroplasts pushed to the edges of the cell by a large vacuole so they can absorb more light
Xylem
Carries water and mineral ions from the roots to the leaf
Made from dead cells, forming hollow, waterproof tubes, through which water passes
Pholem
Carries sucrose away from the leaf
Consists of sieve tubes (through which the sucrose is transported) and companion cells (that provide energy for the transport)
Vascular bundles
Transport tissue in plants made up of xylem and phloem.
Lower epidermis
Protects the inner cells
Thin layer that (apart from guard cells) does not contain chloroplasts, which lets light pass through for photosynthesis
Guard cells
Work in pairs to control the size of the opening of a stoma
Entry and loss of water from the guard cells (due to osmosis) results in changes in their shape; this in turn leads to the opening and closing of the stoma
Stomata
Controls the diffusion of water vapour and gases in and out of the leaf
The size of the opening changes in response to the internal and external environments of the plant
Air spaces in leaf
Allow diffusion of gases throughout the leaf
Spongy mesophyll layer
Site of gas exchange
Cells are loosely spaced, creating air spaces to allow diffusion of gases throughout the leaf
Why is carbon dioxide important for photosynthesis?
To make sugar molecules and oxygen
Which feature is found in a hydrophytic plant?
There is no waxy cuticle.
