Compiled for Ordinary Level Exam 2018

1. transport/vascular tissue

2. Xylem vessels many dead cells
protoplasm or end walls to reduce resistance
to water flowing
hard and rigid substance
to prevent the vessel from collapsing

3. sucrose&amino acids
Sieve Tubes : columns of elongated, thin walled
living cells : sieve tube cells or elements. A
matured sieve tube cell has a thin layer of
cytoplasm in it which is connected to neighbouring
cells through the sieve plates. Each sieve tube has
lost its central vacuole, nucleus and most
organelles. The end walls : sieve plates separating
the cells have lots of minute pores
Companion cells: narrow, thin walled
cell with numerous mitochondria,
cytoplasm and a nucleus. Carries out
metabolic processes needed to keep
the sieve tube cell alive (since it does
not have most of its important
organelles) and provide nutrients and
help the sieve tube cells to transport
manufactured food.
the energy needed to load
sugars from the mesophyll
cells into the sieve tubes by
active transport
rapid flow of

4. vascular
bundle:
arranged
in a ring
around
the pith
layer of cells covering
the stem; protected by a
waxy waterproof cuticle
that greatly reduces
evaporation of water
store up food
substances
cells can divide
and differentiate
to form new
xylem&phloem
tissues

5. *
*
*
*
*
piliferous layer
epidermis: outermost
layer of cells and
bears root hair
alternate
storage tissue
tubular outgrowth of
an epidermal cell to
increase the surface
area to volume ratio
of the root hair cell

6. bi-directional
sucrose flow

7. enable the body to be
cut off; ensures that
the proboscis
remains in the
phloem sieve tube
proboscis : sucking part
test for sugars: Benedict's test test for amino acids: Biuret test

8. accumulation of sugars
water potential decreases thus
water enters through diffusion

9. sugars contain
radioactive carbon

10. mineral
salts
ions

11. Entry of
Water
Each root hair is a fine tubular outgrowth of an epidermal cell containing
cell sap which consists of sugar solution thus it has a lower water potential
than the soil which causes osmosis to occur. This causes the cell to have
a higher water potential thus osmosis happens to the next cell and
continues repeatedly throughout the xylem vessels.
Entry of
ions and
mineral
salts
1) active transport when the concentration of ions in the soil is lower than
the root hair cell ( energy from cellular respiration)
2) diffusion when the concentration is higher
Adaptati
ons
long and narrow
increases surface area to volume
which increases rate of
absorption
cell surface membrane
prevents the cell sap from leaking
which has a lower water
potential=osmosis
many mitochondria
aerobic respiration releases
energy for active transport

13. flowing upwards
lower water potential in xylem vessels

14. Water tends to move up inside very narrow tubes due to the
interactions between water molecules and the surfaces of the tubes
Capillary Tubes

16. relatively
impermeable
to water
surfaces of
the epidermal
cells