Question: 100% NCERT covered from Particular Keyword.Explanations are 100% from NCERT | [Difficult level: Easy] From NCERT NEET Derived Question.
What is common between Chloroplasts, Chromoplasts and
Leucoplasts?
(a) Presence of pigments
(b) Possession of thylakoids and grana
(c) Storage of starch, proteins and lipids
(d) Ability to multiply by a fission-like process
Answer:(d) Ability to multiply by a fission-like process
Chloroplast, chromoplast, and leucoplast are all three are types of plastids.
Leucoplast is a colourless plastid, involved in the storage of starch lipid and proteins. Being colourless, leucoplasts are devoid of any pigments. (This option A is wrong).
Chloroplasts are green coloured plastids containing thylakoids and photosynthetic pigment chlorophyll. They are involved in the photosynthetic production of carbohydrates.
Chromoplasts are plastids responsible for pigment synthesis. They give distinctive colours to different fruits, flowers and ageing leaves in plants.
All the plastids (chromoplast, chromoplast and leucoplast) are thought to be descended from symbiotic prokaryotes and therefore, they all divide by fission like process.
Hence the correct answer is 'Ability to multiply by a fission like process'.\
-plast
👉Kingdom Plantae includes all eukaryotic chlorophyll-containing
organisms commonly called plants. A few members are partially
heterotrophic such as the insectivorous plants or parasites. Bladderwort
and Venus fly trap are examples of insectivorous plants and Cuscuta is a
parasite. The plant cells have an eukaryotic structure with prominent
chloroplasts and cell wall mainly made of cellulose.
👉The members of chlorophyceae are commonly called green algae. The
plant body may be unicellular, colonial or filamentous. They are usually
grass green due to the dominance of pigments chlorophyll a and b. The
pigments are localised in definite chloroplasts. The chloroplasts may be
discoid, plate-like, reticulate, cup-shaped, spiral or ribbon-shaped in
different species. Most of the members have one or more storage bodies
called pyrenoids located in the chloroplasts. Pyrenoids contain protein
besides starch. Some algae may store food in the form of oil droplets.
Green algae usually have a rigid cell wall made of an inner layer of cellulose
and an outer layer of pectose.
👉The members of phaeophyceae or brown algae are found primarily in
marine habitats.The protoplast contains, in addition to plastids, a centrally located vacuole
and nucleus.
👉The collenchyma occurs in layers below the
epidermis in most of the dicotyledonous plants. It is
found either as a homogeneous layer or in patches.
It consists of cells which are much thickened at the
corners due to a deposition of cellulose,
hemicellulose and pectin. Collenchymatous cells
may be oval, spherical or polygonal and often
contain chloroplasts. These cells assimilate food
when they contain chloroplasts. Intercellular spaces
are absent. They provide mechanical support to the
growing parts of the plant such as young stem and
petiole of a leaf.
👉Sclerenchyma consists of long, narrow cells
with thick and lignified cell walls having a few or
numerous pits. They are usually dead and without
protoplasts.
👉The guard cells possess chloroplasts and
regulate the opening and closing of stomata.
👉All tissues except epidermis and vascular bundles constitute the ground
tissue. It consists of simple tissues such as parenchyma, collenchyma
and sclerenchyma. Parenchymatous cells are usually present in cortex,
pericycle, pith and medullary rays, in the primary stems and roots. In
leaves, the ground tissue consists of thin-walled chloroplast containing
cells and is called mesophyll.
👉The tissue between the upper
and the lower epidermis is called the mesophyll. Mesophyll, which
possesses chloroplasts and carry out photosynthesis, is made up of
parenchyma. It has two types of cells – the palisade parenchyma and
the spongy parenchyma.
👉Ribosomes are non-membrane bound organelles found in all cells –
both eukaryotic as well as prokaryotic. Within the cell, ribosomes are
found not only in the cytoplasm but also within the two organelles –
chloroplasts (in plants) and mitochondria and on rough ER.
👉All eukaryotic cells are not identical. Plant and animal cells are different
as the former possess cell walls, plastids and a large central vacuole which
are absent in animal cells.
👉The
endomembrane system include endoplasmic
reticulum (ER), golgi complex, lysosomes and
vacuoles. Since the functions of the mitochondria,
chloroplast and peroxisomes are not coordinated
with the above components, these are not
considered as part of the endomembrane system.
👉The
vacuole is bound by a single membrane called tonoplast.
👉In plants, the tonoplast facilitates the transport of a number of ions
and other materials against concentration gradients into the vacuole, hence
their concentration is significantly higher in the vacuole than in the
cytoplasm.
👉Plastids
Plastids are found in all plant cells and in euglenoides. These are easily
observed under the microscope as they are large. They bear some specific
pigments, thus imparting specific colours to the plants. Based on the
type of pigments plastids can be classified into chloroplasts,
chromoplasts and leucoplasts.
The chloroplasts contain chlorophyll and carotenoid pigments which
are responsible for trapping light energy essential for photosynthesis. In
the chromoplasts fat soluble carotenoid pigments like carotene,
xanthophylls and others are present. This gives the part of the plant a
yellow, orange or red colour. The leucoplasts are the colourless plastids
of varied shapes and sizes with stored nutrients: Amyloplasts store
carbohydrates (starch), e.g., potato; elaioplasts store oils and fats whereas
the aleuroplasts store proteins.
Majority of the chloroplasts of the green
plants are found in the mesophyll cells of
the leaves. These are lens-shaped, oval,
spherical, discoid or even ribbon-like
organelles having variable length (5-10μm)
and width (2-4μm). Their number varies
from 1 per cell of the Chlamydomonas, a
green alga to 20-40 per cell in the mesophyll.
Like mitochondria, the chloroplasts are
also double membrane bound. Of the two,
the inner chloroplast membrane is relatively
less permeable. The space limited by the
inner membrane of the chloroplast is called the stroma. A number of organised
flattened membranous sacs called the thylakoids, are present in the stroma
(Figure 8.8). Thylakoids are arranged in stacks like the piles of coins called
grana (singular: granum) or the intergranal thylakoids. In addition, there are
flat membranous tubules called the stroma lamellae connecting the thylakoids
of the different grana. The membrane of the thylakoids enclose a space called
a lumen. The stroma of the chloroplast contains enzymes required for the
synthesis of carbohydrates and proteins. It also contains small, doublestranded
circular DNA molecules and ribosomes. Chlorophyll pigments are
present in the thylakoids. The ribosomes of the chloroplasts are smaller (70S)
than the cytoplasmic ribosomes (80S).
