BIOLOGY NOTES: CLASS - IX (NCERT BASED) Page|1
Chapter 6: Tissues
(up to Simple Permanent Tissues) Part: 1
Introduction
• All organisms on Earth are composed of one or more cells.
• In unicellular organisms, a single cell performs all functions necessary for the
organism's survival.
• Multicellular organisms possess more intricate body structures and systems.
• In multicellular organisms, individual cells collaborate as a union to fulfil specific
functions, collectively referred to as tissues.
• For instance, the skin, the largest tissue in the human body, comprises millions of
cells working in union to facilitate body protection.
• This chapter focuses on the types of tissues found in plants and animals
1. MERISTEMATIC TISSUES IN PLANTS
• Meristems serve as the growth points of plants,
representing localized regions comprising thin-walled,
densely packed living cells.
• These cells frequently undergo mitosis and can
continue dividing indefinitely.
• Meristems play a crucial role in the differentiation of
most plant body parts, although cell division can
occasionally occur in other regions. A growing plant
• Three types of meristems exist:
1.1. Apical Meristems:
• These are found at the shoot apex
and root apex.
• Shoot apical meristems contribute
to the differentiation of primary
stem, leaves, and flowers, while
root apical meristems are
responsible for primary root tissue
production.
• Both types of apical meristems
facilitate extension growth and
self-renewal.
• Additionally, shoot apical
meristems initiate lateral organs
(leaves) in a regular nodal
arrangement, with each node bearing a single leaf, a pair of leaves, or a
whorl of leaves.
BIOLOGY NOTES: CLASS - IX | SUJITH PB
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1.2. Intercalary Meristems:
• These meristematic tissues are responsible for making the shoot axis
longer. It can happen either by cells dividing and growing throughout the
youngest parts or in a specific area near the base of the internode.
1.3. Lateral Meristems:
• These are crucial for stem thickening growth.
• They encompass vascular cambium, primary, and secondary thickening
meristems.
• Lateral meristems are localized in regions parallel to the long axis of a shoot
or root, primarily situated in the pericyclic zone at the junction between
vascular tissue and cortex.
• Additionally, the phellogen (cork cambium) is a
type of lateral meristem that forms in the stem
or root cortex, creating a protective corky layer.
• Phellogen can also develop in regions of
wounds or at the point of leaf abscission.
1.4. Properties of Meristematic Tissues
• Nucleus is larger
• RER is present, but SER is undeveloped
• Undifferentiated plastids are found
• Vacuoles are present but small in number and size
Q1) Why do meristematic cells have small vacuoles, and what are the
advantages of this? (3 marks)
Answer: Meristematic cells have small vacuoles because they need ample space for
rapid growth and division, ensuring efficient cytoplasmic activity. This compact
structure contributes to their mechanical strength, making them resilient. Additionally,
small vacuoles allow these cells to retain essential nutrients for energy. As
meristematic cells mature and specialize, larger vacuoles may develop for specific
functions, but initially, small vacuoles support their primary role in vigorous growth and
strength.
2. PERMANENT TISSUES IN PLANTS
• Due to continuous meristematic division, certain daughter cells undergo a
crucial process known as “differentiation”.
• This process entails some cells ceasing their division either permanently or
temporarily, leading to them being referred to as “differentiated”.
Differentiation
Meristematic Cells Permanent Cells (stomata)
BIOLOGY NOTES: CLASS - IX | SUJITH PB
Chapter 6: Tissues
(up to Simple Permanent Tissues) Part: 1
Introduction
• All organisms on Earth are composed of one or more cells.
• In unicellular organisms, a single cell performs all functions necessary for the
organism's survival.
• Multicellular organisms possess more intricate body structures and systems.
• In multicellular organisms, individual cells collaborate as a union to fulfil specific
functions, collectively referred to as tissues.
• For instance, the skin, the largest tissue in the human body, comprises millions of
cells working in union to facilitate body protection.
• This chapter focuses on the types of tissues found in plants and animals
1. MERISTEMATIC TISSUES IN PLANTS
• Meristems serve as the growth points of plants,
representing localized regions comprising thin-walled,
densely packed living cells.
• These cells frequently undergo mitosis and can
continue dividing indefinitely.
• Meristems play a crucial role in the differentiation of
most plant body parts, although cell division can
occasionally occur in other regions. A growing plant
• Three types of meristems exist:
1.1. Apical Meristems:
• These are found at the shoot apex
and root apex.
• Shoot apical meristems contribute
to the differentiation of primary
stem, leaves, and flowers, while
root apical meristems are
responsible for primary root tissue
production.
• Both types of apical meristems
facilitate extension growth and
self-renewal.
• Additionally, shoot apical
meristems initiate lateral organs
(leaves) in a regular nodal
arrangement, with each node bearing a single leaf, a pair of leaves, or a
whorl of leaves.
BIOLOGY NOTES: CLASS - IX | SUJITH PB
, BIOLOGY NOTES: CLASS - IX (NCERT BASED) Page|2
1.2. Intercalary Meristems:
• These meristematic tissues are responsible for making the shoot axis
longer. It can happen either by cells dividing and growing throughout the
youngest parts or in a specific area near the base of the internode.
1.3. Lateral Meristems:
• These are crucial for stem thickening growth.
• They encompass vascular cambium, primary, and secondary thickening
meristems.
• Lateral meristems are localized in regions parallel to the long axis of a shoot
or root, primarily situated in the pericyclic zone at the junction between
vascular tissue and cortex.
• Additionally, the phellogen (cork cambium) is a
type of lateral meristem that forms in the stem
or root cortex, creating a protective corky layer.
• Phellogen can also develop in regions of
wounds or at the point of leaf abscission.
1.4. Properties of Meristematic Tissues
• Nucleus is larger
• RER is present, but SER is undeveloped
• Undifferentiated plastids are found
• Vacuoles are present but small in number and size
Q1) Why do meristematic cells have small vacuoles, and what are the
advantages of this? (3 marks)
Answer: Meristematic cells have small vacuoles because they need ample space for
rapid growth and division, ensuring efficient cytoplasmic activity. This compact
structure contributes to their mechanical strength, making them resilient. Additionally,
small vacuoles allow these cells to retain essential nutrients for energy. As
meristematic cells mature and specialize, larger vacuoles may develop for specific
functions, but initially, small vacuoles support their primary role in vigorous growth and
strength.
2. PERMANENT TISSUES IN PLANTS
• Due to continuous meristematic division, certain daughter cells undergo a
crucial process known as “differentiation”.
• This process entails some cells ceasing their division either permanently or
temporarily, leading to them being referred to as “differentiated”.
Differentiation
Meristematic Cells Permanent Cells (stomata)
BIOLOGY NOTES: CLASS - IX | SUJITH PB
