FORM TWO TOPICS
1. a) i) Define transport
• movement of substances from one part of the body to another
ii) Explain the necessity of transport in plants and animals
• make nutrients move from one point to another
• movement of respiratory gases i.e. oxygen and carbon IV oxide
• elimination of metabolic wastes
• movement of hormones
• movement of water
• movement of salts
• movement of enzymes
b) i) Describe the structure and function of root hair
• root hairs are found near the root tip
• they are cells with elongated finger-like projections which are in contact with soil particles
• they are permeable to water and mineral salts hence are used to absorb water and mineral salts
• There large number offers a large surface area for absorption of water and mineral salts.
ii) State ways in which the root hairs are adapted to their functions
• the root hair is long/narrow/numerous to increase surface area for absorption of water and mineral
salts
• many mitochondria in cytoplasm to supply energy for active transport of mineral salts
• are thin walled to speed up rate of absorption of water and mineral salts
c) i) Compare the internal structure of a dicotyledonous root and a monocotyledonous root
Dicot root
Monocot root
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,ii) State the similarities and differences between a dicotyledonous and monocotyledonous root
Similarities
• both used for anchorage and absorption of water and mineral salts
• both have root hairs, epidermis, pericycle, cortex, endodermis and vascular bundles (xylem and
phloem)
• both may be used to store food/storage organs
•
Differences
Monocotyledonous Dicotyledonous
• phloem and xylem are arranged in • phloem lies between radial rays of
ring form alternately central xylem(star shaped)
• pith present • pith absent
iii) Compare the internal structure of a monocotyledonous and dicotyledonous stem
Monocotyledonous Dicotyledonous
i) Give the similarities and differences between a monocotyledonous and dicotyledonous
stem
Similarities
• both are used for protection
• both conduct water, salts and food
• both have epidermis, cortex, pericycle and vascular bundles
Differences
Monocotyledonous Dicotyledonous
• vascular bundles are many and • vascular bundles are few and
scattered arranged in a concentric ring near
• some have hollow pith or pith is the epidermis
absent • pith large and well developed
• no cambium layer therefore cannot • presence of cambium therefore
undergo secondary growth undergoes secondary growth
• very little cortex • cortex has several layers of cells
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, i) State the differences between the internal structure of a root and a stem.
Root Stem
• has root hairs • no root hairs
• no cuticle • cuticle present
• xylem and phloem arranged • xylem and phloem arranged on the
alternately same radii
• in xylem, the small vessels are • in xylem, the smallest vessels are
towards the outside towards the inside
• cortex is the widest tissue • pith is the widest tissue
c) i) Name the transport structures of a flowering plant
• xylem vessels and tracheids transport water and mineral salts from the soil
• Phloem vessels translocate manufactured food from leaves to other parts of the body.
ii) State the ways in which xylem vessels are adapted to their function
• lignified/thickened to prevent collapsing
• narrow to facilitate capillary
• no cross walls for continuous flow/column of water
• have bordered pits for lateral movement of water
a) i) Why do flowering plants need water?
• photosynthesis
• transport
• turgidity which helps in plant support
• solvent i.e. medium for chemical reactions
• cooling effect during transpiration
• seed germination
ii) Describe the movement of water from the soil to the leaves of a tall plant
Soil
• water exists as a thin film in the soil, between soil particles
• the concentration of cell sap of root hair is greater than that of the surrounding solution in the soil,
thus drawing the water molecules across the cell wall and cell membrane into the root hair by
osmosis
• water drawn into the root hair cell dilutes the cell sap making it less concentrated than that in the
adjacent cortex cells of the root
• due to osmotic gradient water moves from the root hair cells into the cortex by osmosis, from cell to
cell by osmosis, across the endodermis by active transport into xylem vessels of the root that conduct
water into xylem vessels of the stem into xylem vessels of the leaves
Stem
• Once in the stem water moves up the plant aided by the narrowness of the xylem vessels (capillary),
root pressure, attraction of water molecules to each other (cohesion). Attraction of water molecules
to the walls (adhesion)
• from the stem water enters the xylem of leaves
• water moves in the xylem vessels of the stem in a continuous (uninterrupted) water column up to the
tree leaves
www.arena.co.ke 0713779527
, Leaves
• once in the leaves water moves into the mesophyll cells by osmosis
• as water vaporizes from the spongy mesophyll cells their sap becomes more concentrated than the
adjacent cells
• as the result water flows into the cell from other surrounding cells which in turn takes in water from
xylem vessels within the leaf veins
• this creates a pull(suction force) called transpiration pull that pulls a stream of water from xylem
vessels in the stem and roots
• The transpiration pull maintains a continuous column of water from the roots to the leaves.
iii) Name the process by which mineral salts enter into a plant
• active transport
• diffusion
i) Explain the forces that make water and mineral salts move through a plant
• mineral salts are taken up due to diffusion because of the concentration gradient between the mineral
ions in sap and those in soil solution
• active transport involves energy in form of ATP due to respiration which forces mineral salts through
a plant against a concentration gradient
• water moves by osmosis through a semi-permeable membrane of root hairs and between cells of
stem
• in stem water moves by cohesion(attraction of water molecules to each other)
• it also moves by adhesion(attraction of water molecules to walls)
• capillarity is due to narrowness of xylem vessels
• transpiration pull occurs when water vapour evaporates from sub-stomatal chambers into the air
• root pressure is a force that pushes water up the stem from the roots and causes guttation /exudation
ii) Explain the uptake of mineral salts by plants
• plants require mineral salts for metabolism and proper functioning of their bodies
• mineral salts are taken up from the soil into the root hairs in form of solution by active transport
which requires energy
• active transport involves substances called carriers taken up together with water and are then carried
to the stems and leaves
• the main process involved in uptake and movement of mineral salts is active transport
b) i) What is transpiration?
• loss of water from plant to the atmosphere
ii) Name the sites through which transpiration takes place in a plant
• stomata (stomatal transpiration)
• lenticels (lenticular transpiration)
• cuticle(cuticular transpiration)
iii) State the importance of transpiration to plants
• cooling the plant
www.arena.co.ke 0713779527
1. a) i) Define transport
• movement of substances from one part of the body to another
ii) Explain the necessity of transport in plants and animals
• make nutrients move from one point to another
• movement of respiratory gases i.e. oxygen and carbon IV oxide
• elimination of metabolic wastes
• movement of hormones
• movement of water
• movement of salts
• movement of enzymes
b) i) Describe the structure and function of root hair
• root hairs are found near the root tip
• they are cells with elongated finger-like projections which are in contact with soil particles
• they are permeable to water and mineral salts hence are used to absorb water and mineral salts
• There large number offers a large surface area for absorption of water and mineral salts.
ii) State ways in which the root hairs are adapted to their functions
• the root hair is long/narrow/numerous to increase surface area for absorption of water and mineral
salts
• many mitochondria in cytoplasm to supply energy for active transport of mineral salts
• are thin walled to speed up rate of absorption of water and mineral salts
c) i) Compare the internal structure of a dicotyledonous root and a monocotyledonous root
Dicot root
Monocot root
www.arena.co.ke 0713779527
,ii) State the similarities and differences between a dicotyledonous and monocotyledonous root
Similarities
• both used for anchorage and absorption of water and mineral salts
• both have root hairs, epidermis, pericycle, cortex, endodermis and vascular bundles (xylem and
phloem)
• both may be used to store food/storage organs
•
Differences
Monocotyledonous Dicotyledonous
• phloem and xylem are arranged in • phloem lies between radial rays of
ring form alternately central xylem(star shaped)
• pith present • pith absent
iii) Compare the internal structure of a monocotyledonous and dicotyledonous stem
Monocotyledonous Dicotyledonous
i) Give the similarities and differences between a monocotyledonous and dicotyledonous
stem
Similarities
• both are used for protection
• both conduct water, salts and food
• both have epidermis, cortex, pericycle and vascular bundles
Differences
Monocotyledonous Dicotyledonous
• vascular bundles are many and • vascular bundles are few and
scattered arranged in a concentric ring near
• some have hollow pith or pith is the epidermis
absent • pith large and well developed
• no cambium layer therefore cannot • presence of cambium therefore
undergo secondary growth undergoes secondary growth
• very little cortex • cortex has several layers of cells
www.arena.co.ke 0713779527
, i) State the differences between the internal structure of a root and a stem.
Root Stem
• has root hairs • no root hairs
• no cuticle • cuticle present
• xylem and phloem arranged • xylem and phloem arranged on the
alternately same radii
• in xylem, the small vessels are • in xylem, the smallest vessels are
towards the outside towards the inside
• cortex is the widest tissue • pith is the widest tissue
c) i) Name the transport structures of a flowering plant
• xylem vessels and tracheids transport water and mineral salts from the soil
• Phloem vessels translocate manufactured food from leaves to other parts of the body.
ii) State the ways in which xylem vessels are adapted to their function
• lignified/thickened to prevent collapsing
• narrow to facilitate capillary
• no cross walls for continuous flow/column of water
• have bordered pits for lateral movement of water
a) i) Why do flowering plants need water?
• photosynthesis
• transport
• turgidity which helps in plant support
• solvent i.e. medium for chemical reactions
• cooling effect during transpiration
• seed germination
ii) Describe the movement of water from the soil to the leaves of a tall plant
Soil
• water exists as a thin film in the soil, between soil particles
• the concentration of cell sap of root hair is greater than that of the surrounding solution in the soil,
thus drawing the water molecules across the cell wall and cell membrane into the root hair by
osmosis
• water drawn into the root hair cell dilutes the cell sap making it less concentrated than that in the
adjacent cortex cells of the root
• due to osmotic gradient water moves from the root hair cells into the cortex by osmosis, from cell to
cell by osmosis, across the endodermis by active transport into xylem vessels of the root that conduct
water into xylem vessels of the stem into xylem vessels of the leaves
Stem
• Once in the stem water moves up the plant aided by the narrowness of the xylem vessels (capillary),
root pressure, attraction of water molecules to each other (cohesion). Attraction of water molecules
to the walls (adhesion)
• from the stem water enters the xylem of leaves
• water moves in the xylem vessels of the stem in a continuous (uninterrupted) water column up to the
tree leaves
www.arena.co.ke 0713779527
, Leaves
• once in the leaves water moves into the mesophyll cells by osmosis
• as water vaporizes from the spongy mesophyll cells their sap becomes more concentrated than the
adjacent cells
• as the result water flows into the cell from other surrounding cells which in turn takes in water from
xylem vessels within the leaf veins
• this creates a pull(suction force) called transpiration pull that pulls a stream of water from xylem
vessels in the stem and roots
• The transpiration pull maintains a continuous column of water from the roots to the leaves.
iii) Name the process by which mineral salts enter into a plant
• active transport
• diffusion
i) Explain the forces that make water and mineral salts move through a plant
• mineral salts are taken up due to diffusion because of the concentration gradient between the mineral
ions in sap and those in soil solution
• active transport involves energy in form of ATP due to respiration which forces mineral salts through
a plant against a concentration gradient
• water moves by osmosis through a semi-permeable membrane of root hairs and between cells of
stem
• in stem water moves by cohesion(attraction of water molecules to each other)
• it also moves by adhesion(attraction of water molecules to walls)
• capillarity is due to narrowness of xylem vessels
• transpiration pull occurs when water vapour evaporates from sub-stomatal chambers into the air
• root pressure is a force that pushes water up the stem from the roots and causes guttation /exudation
ii) Explain the uptake of mineral salts by plants
• plants require mineral salts for metabolism and proper functioning of their bodies
• mineral salts are taken up from the soil into the root hairs in form of solution by active transport
which requires energy
• active transport involves substances called carriers taken up together with water and are then carried
to the stems and leaves
• the main process involved in uptake and movement of mineral salts is active transport
b) i) What is transpiration?
• loss of water from plant to the atmosphere
ii) Name the sites through which transpiration takes place in a plant
• stomata (stomatal transpiration)
• lenticels (lenticular transpiration)
• cuticle(cuticular transpiration)
iii) State the importance of transpiration to plants
• cooling the plant
www.arena.co.ke 0713779527
