Buyer: Victoria Proctor ()
Biology Questions and Answers
In 1665 Robert Hooke, an
Cell Structure English scientist, published his
book Micrographia, in which
he described that pieces of
cork viewed under the
1. What is cell theory?
microscope presented small
Cell theory asserts that the cell is the
cavities similar to pores which
constituent unit of living beings. were filled with air. Based on
later knowledge, of what were
Before the discovery of the cell, it was the walls of those cavities
not recognized that living beings were constituted? What is the
made of building blocks like cells.
historical importance of that
The cell theory is one of the basic observation?
theories of Biology.
The walls of the cavities observed by
Hooke were the walls of the plant cells
that form the tissue. The observation
2. Are there living beings led to the discovery of the cells, a fact
without cells? only possible after the invention of the
microscope. In that work, Hooke
established the term “cell”, now widely
Viruses are considered the only living used in Biology, to designate those
beings that do not have cells. Viruses cavities seen under the microscope.
are constituted by genetic material
(DNA or RNA) enwrapped by a protein
capsule. They do not have membranes
and cell organelles nor do they have
4. What are the two big
self-metabolism.
groups into which cells are
3. classified?
Cells can be classified as eukaryotic or
prokaryotic.
Prokaryotic cell is that without a
delimited nucleus. Eukaryotic cells are
those with nucleus delimited by
membrane.
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Biology Questions and Answers
pointing to the exterior of the layer and
5. Do bacteria cells have a the non-polar phospholipid chains in the
nucleus? interior. Proteins can be found
embedded in the lipid bilayer and there
In bacteria the genetic material is are also some carbohydrates bound to
dispersed in the cytosol and there is no proteins and to phospholipids in the
internal membrane that delimits a outer face of the membrane.
nucleus.
9. What is the difference
6. Are there any bacteria between plasma membrane
made of more than one cell? and cell wall?
There are no pluricellular bacteria. All Plasma membrane and cell wall are not
bacteria are unicellular prokaryotic. the same thing. Plasma membrane, also
called cell membrane, is the outer
membrane common to all living cells
and it is made of a phospholipid bilayer,
7. What is the plasma embedded proteins and some appended
membrane of the cell? What carbohydrates.
are its main functions?
Because cell membranes are fragile, in
some types of cells there are even outer
The plasma membrane is the outer
structures that support and protect the
membrane of the cell, it delimits the cell
membrane, like the cellulose wall of
itself and a cell interior with specific
plant cells and the chitin wall of some
conditions for the cellular function.
fungi cells. Most bacteria also present
Since it is selectively permeable, the
an outer cell wall made of
plasma membrane has an important
peptidoglycans and other organic
role for the passage of substances
substances.
inwards or outwards.
8. What are the chemical 10. What are the main
substances that compose the respective constituents of cell
plasma membrane? walls in bacteria, protists,
fungi and plants?
The main constituents of the plasma
membrane are phospholipids, proteins In bacteria the cell wall is made of
and carbohydrates. The phospholipds, peptidoglycans; among protists algae
amphipathic molecules, are regularly have cell walls made of cellulose; in
organized in the membrane according to fungi, the cell wall is made of chitin (the
their polarity: two layers of same substance that makes the
phospholipids form the lipid bilayer with
the polar part of the phospholipids
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46
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Biology Questions and Answers
exoskeleton of arthropods); in plants, and thus they are eukaryotic cells; in
the cell wall is made of cellulose too. these cells the genetic material is
located within the nucleus. Bacterial
cells (cells of living beings of the
kingdom Monera) do not have organized
cellular nuclei and so they are
11. Do membranes form only
prokaryotic cells and their genetic
the outer wrapping of cells? material is found dispersed in the
cytosol.
Lipid membranes do not form only the
outer cover of cells. Cell organelles,
such as the Golgi complex,
mitochondria, chloroplasts, lysosomes, 14. What are the three main
the endoplasmic reticula and the parts of a eukaryotic cell?
nucleus, are delimited by membranes
too.
The eukaryotic cell can be divided into
two main portions: the cell membrane
that separates the intracellular space
from the outer space physically
12. Which type of cell came
delimiting the cell; the cytoplasm, the
first in evolution - the interior portion filled with cytosol (the
eukaryotic cell or the aqueous fluid inside the cell); and the
prokaryotic cell? nucleus, the membrane-delimited
internal region that contains the genetic
This is an interesting problem of material.
biological evolution. The most accepted
hypothesis asserts that the more simple
cell, the prokaryotic cell, appeared
earlier in evolution than the more 15. What are the main
complex eukaryotic cell. The structures within the cell
endosymbiotic hypothesis, for example, nucleus?
affirms that aerobic eukaryotic cells
appeared from the mutualist ecological
Within the cell nucleus the main
interaction between aerobic prokaryotes
structures are: the nucleolus, an
and primitive anaerobic eukaryotes.
optically dense region, spherical shaped,
where there are concentrated ribosomal
RNA (rRNA) associated to proteins
(there may be more than one nucleolus
13. Concerning the presence in a nucleus); the chromatin, made of
of the nucleus what is the DNA molecules dispersed in the nuclear
difference between animal matrix during the cell interphase; the
and bacterial cells? karyotecha, or nuclear membrane, the
membrane that delimits the nucleus.
Animal cells (cells of living beings of the
kingdom Animalia) have an interior
membrane that delimits a cell nucleus
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Biology Questions and Answers
16. What are the substances What is the name of the
that constitute the chromatin? membrane that delimits the
What is the difference nucleus? To which component
between chromatin and of the cell structure is that
chromosome? membrane contiguous?
The chromatin, dispersed in the The nuclear membrane is also called
nucleus, is a set of filamentous DNA karyotheca. The nuclear membrane is
molecules associated to nuclear proteins continuous to the endoplasmic reticulum
called histones. Each DNA filament is a membrane.
double helix of DNA and thus a
chromosome.
20. What are the main
cytoplasmic structures
17. What is the fluid that fills present in animal cells?
the nucleus called?
The main cytoplasmic structures of the
The aqueous fluid that fills the nuclear cell are the centrioles, the cytoskeleton,
region is called karyolymph, or lysosomes, mitochondria, peroxisomes,
nucleoplasm. In the fluid there are the Golgi apparatus, the endoplasmic
proteins, enzymes and other important reticula and ribosomes.
substances for the nuclear metabolism.
21. What are cytoplasmic
18. Of what substances is the inclusions?
nucleolus made? Is there a
membrane around the Cytoplasmic inclusions are cytoplasmic
nucleolus? molecular aggregates, such as
pigments, organic polymers and
crystals. They are not considered cell
Nucleolus is a region within the nucleus
organelles.
made of ribosomal RNA (rRNA) and
proteins. It is not delimited by
Fat droplets and glycogen granules are
membrane.
examples of cytoplasmic inclusions.
19.
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48
Biology Questions and Answers
In 1665 Robert Hooke, an
Cell Structure English scientist, published his
book Micrographia, in which
he described that pieces of
cork viewed under the
1. What is cell theory?
microscope presented small
Cell theory asserts that the cell is the
cavities similar to pores which
constituent unit of living beings. were filled with air. Based on
later knowledge, of what were
Before the discovery of the cell, it was the walls of those cavities
not recognized that living beings were constituted? What is the
made of building blocks like cells.
historical importance of that
The cell theory is one of the basic observation?
theories of Biology.
The walls of the cavities observed by
Hooke were the walls of the plant cells
that form the tissue. The observation
2. Are there living beings led to the discovery of the cells, a fact
without cells? only possible after the invention of the
microscope. In that work, Hooke
established the term “cell”, now widely
Viruses are considered the only living used in Biology, to designate those
beings that do not have cells. Viruses cavities seen under the microscope.
are constituted by genetic material
(DNA or RNA) enwrapped by a protein
capsule. They do not have membranes
and cell organelles nor do they have
4. What are the two big
self-metabolism.
groups into which cells are
3. classified?
Cells can be classified as eukaryotic or
prokaryotic.
Prokaryotic cell is that without a
delimited nucleus. Eukaryotic cells are
those with nucleus delimited by
membrane.
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45
,Buyer: Victoria Proctor ()
Biology Questions and Answers
pointing to the exterior of the layer and
5. Do bacteria cells have a the non-polar phospholipid chains in the
nucleus? interior. Proteins can be found
embedded in the lipid bilayer and there
In bacteria the genetic material is are also some carbohydrates bound to
dispersed in the cytosol and there is no proteins and to phospholipids in the
internal membrane that delimits a outer face of the membrane.
nucleus.
9. What is the difference
6. Are there any bacteria between plasma membrane
made of more than one cell? and cell wall?
There are no pluricellular bacteria. All Plasma membrane and cell wall are not
bacteria are unicellular prokaryotic. the same thing. Plasma membrane, also
called cell membrane, is the outer
membrane common to all living cells
and it is made of a phospholipid bilayer,
7. What is the plasma embedded proteins and some appended
membrane of the cell? What carbohydrates.
are its main functions?
Because cell membranes are fragile, in
some types of cells there are even outer
The plasma membrane is the outer
structures that support and protect the
membrane of the cell, it delimits the cell
membrane, like the cellulose wall of
itself and a cell interior with specific
plant cells and the chitin wall of some
conditions for the cellular function.
fungi cells. Most bacteria also present
Since it is selectively permeable, the
an outer cell wall made of
plasma membrane has an important
peptidoglycans and other organic
role for the passage of substances
substances.
inwards or outwards.
8. What are the chemical 10. What are the main
substances that compose the respective constituents of cell
plasma membrane? walls in bacteria, protists,
fungi and plants?
The main constituents of the plasma
membrane are phospholipids, proteins In bacteria the cell wall is made of
and carbohydrates. The phospholipds, peptidoglycans; among protists algae
amphipathic molecules, are regularly have cell walls made of cellulose; in
organized in the membrane according to fungi, the cell wall is made of chitin (the
their polarity: two layers of same substance that makes the
phospholipids form the lipid bilayer with
the polar part of the phospholipids
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46
,Buyer: Victoria Proctor ()
Biology Questions and Answers
exoskeleton of arthropods); in plants, and thus they are eukaryotic cells; in
the cell wall is made of cellulose too. these cells the genetic material is
located within the nucleus. Bacterial
cells (cells of living beings of the
kingdom Monera) do not have organized
cellular nuclei and so they are
11. Do membranes form only
prokaryotic cells and their genetic
the outer wrapping of cells? material is found dispersed in the
cytosol.
Lipid membranes do not form only the
outer cover of cells. Cell organelles,
such as the Golgi complex,
mitochondria, chloroplasts, lysosomes, 14. What are the three main
the endoplasmic reticula and the parts of a eukaryotic cell?
nucleus, are delimited by membranes
too.
The eukaryotic cell can be divided into
two main portions: the cell membrane
that separates the intracellular space
from the outer space physically
12. Which type of cell came
delimiting the cell; the cytoplasm, the
first in evolution - the interior portion filled with cytosol (the
eukaryotic cell or the aqueous fluid inside the cell); and the
prokaryotic cell? nucleus, the membrane-delimited
internal region that contains the genetic
This is an interesting problem of material.
biological evolution. The most accepted
hypothesis asserts that the more simple
cell, the prokaryotic cell, appeared
earlier in evolution than the more 15. What are the main
complex eukaryotic cell. The structures within the cell
endosymbiotic hypothesis, for example, nucleus?
affirms that aerobic eukaryotic cells
appeared from the mutualist ecological
Within the cell nucleus the main
interaction between aerobic prokaryotes
structures are: the nucleolus, an
and primitive anaerobic eukaryotes.
optically dense region, spherical shaped,
where there are concentrated ribosomal
RNA (rRNA) associated to proteins
(there may be more than one nucleolus
13. Concerning the presence in a nucleus); the chromatin, made of
of the nucleus what is the DNA molecules dispersed in the nuclear
difference between animal matrix during the cell interphase; the
and bacterial cells? karyotecha, or nuclear membrane, the
membrane that delimits the nucleus.
Animal cells (cells of living beings of the
kingdom Animalia) have an interior
membrane that delimits a cell nucleus
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, Buyer: Victoria Proctor ()
Biology Questions and Answers
16. What are the substances What is the name of the
that constitute the chromatin? membrane that delimits the
What is the difference nucleus? To which component
between chromatin and of the cell structure is that
chromosome? membrane contiguous?
The chromatin, dispersed in the The nuclear membrane is also called
nucleus, is a set of filamentous DNA karyotheca. The nuclear membrane is
molecules associated to nuclear proteins continuous to the endoplasmic reticulum
called histones. Each DNA filament is a membrane.
double helix of DNA and thus a
chromosome.
20. What are the main
cytoplasmic structures
17. What is the fluid that fills present in animal cells?
the nucleus called?
The main cytoplasmic structures of the
The aqueous fluid that fills the nuclear cell are the centrioles, the cytoskeleton,
region is called karyolymph, or lysosomes, mitochondria, peroxisomes,
nucleoplasm. In the fluid there are the Golgi apparatus, the endoplasmic
proteins, enzymes and other important reticula and ribosomes.
substances for the nuclear metabolism.
21. What are cytoplasmic
18. Of what substances is the inclusions?
nucleolus made? Is there a
membrane around the Cytoplasmic inclusions are cytoplasmic
nucleolus? molecular aggregates, such as
pigments, organic polymers and
crystals. They are not considered cell
Nucleolus is a region within the nucleus
organelles.
made of ribosomal RNA (rRNA) and
proteins. It is not delimited by
Fat droplets and glycogen granules are
membrane.
examples of cytoplasmic inclusions.
19.
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