BIOLOGY MID-SEMESTER

1. Biomimetics: Some engineering designs and technological innovations are designed by

adopting examples from biology or nature. These are termed as biomimicry.
2. Cats can see in the dark unlike us, because of the presence of a reflective layer called the
‘tapetum lucidium’ in their eyes.
3. Biomechanics: Study of mechanics of how muscles, bones, tendons, and ligaments or skeletal
system work together to produce movement of a living body with response to external forces
and stimuli.
4. Nanomechanics: Deals with the simulations and measurements of mechanical behaviours of
nanomaterials at nanoscale levels, which is used in biology and medicine.
5. Computational fluid dynamics (CFD): Engineering tool that connects mechanics to
mathematics and software programming to execute simulation performing how a fluid (liquid or
gas) flows
6. Bioinformatics integrates computer science, biology, statistics, mathematics, and medical
sciences etc to understand the biological system or to solve biology-based problems
7. Bioconcrete: (PYQ)
a. Concrete prepared through the addition of bacteria (e.g. Bacillus), and calcium lactate that
aids in sealing the cracks that appear in it.
b. When concrete structure has cracks, water seeped into it that activate bacterial spores to
germinate. Then, the bacteria start consuming the calcium lactate, which gets converted
into insoluble limestone that solidifies on the cracked surface, thereby sealing it up
8. Bioceramics: (PYQ)
a. Ceramics used for the repair and reconstruction of human body parts, such as synthetic
bones and dental implants etc.
b. Hydroxyapatite (HA), a bioceramic reinforced by polyethylene composites, used as
synthetic bone substitute

9. Biomining: (PYQ)
a. Process in mining engineering that deals with extraction of metals of from rock ores,
mineral concentrates, or mine waste by using microorganisms
b. This was adopted seeing some rock-munching bacteria, such as Acidithiobacillus
ferrooxidans
c. iron- and sulfur-oxidizing microbes are usually used in biomining which oxidizes
minerals containing insoluble metal sulfides into their soluble sulfate forms.
d. Metals are recovered from the metal sulfates that are biomined into the water, cleaning up
the mining sites
10. Sharklet: (PYQ)
a. Material known as “Sharklet” is used on ships to inhibit the growth of marine microbes
on its surface.
 b. This was designed mimicking the pattern of ‘dermal denticles’ of Shark skin. The
microscopic “dermal denticles” help the Shark to create a low-pressure zone that enables
it to move forward with less drag and fend-off microorganisms unlike other aquatic
species.
11. Synthe c biology:
a. Combines biology with engineering/industrial design
b. Considers living systems as programmable at the genetic level and offers the possibility
of applying systematic design approaches to constructing new biological systems or cells
with human-defined functions
12. In summary, living organisms: (PYQ)
a. are composed of cells (Cellular Organization)
b. are complex and ordered (Ordered Complexity)
c. respond to their environment (Sensitivity)
d. can Grow, Develop and Reproduce
e. obtain and use energy (Energy Utilization)
f. maintain internal balance (Homeostasis)
g. allow for Evolutionary Adaptation
13. Homeostasis: Examples:
a. Water balance inside and outside of cell
b. Human body temperature
c. Blood pH is tightly regulated (7.40).
d. Pancreatic hormones work to regulate blood glucose.
e. Cells function best when these are in balance
14. Classification of Organisms: (PYQ)
a. Unicellular (Amoeba, bacteria, protozoa, and yeast) and multicellular (animals, plants,
fungus)
b. Prokaryotes (most primitive organisms) and eukaryotes
c. Autotrophs (synthesise their own food), heterotrophs (cannot synthesise their own
food), and lithotrophs (uses inorganic compounds, nitrifying/iron-oxidizing bacteria)
d. Aminotelic (aquatic animals including fishes): excrete ammonia as their waste product
Ureotelic (mammals, adult amphibians): Ureotelic organisms are those that excrete urea
as their waste product.
Uricotelic (birds, insects, land snails, many reptiles): Uricotelic organisms are those that
excrete uric acid as their waste product
15. Taxonomy (classification system):
a. Two-kingdom classification by Carolus Linnaeus
based on the mode of their nutrition and mobility
i. Animalia (unicellular protozoans and multicellular animals)
ii. Plantae (remaining organisms)
b. Three-kingdom classification by Ernst Haeckel
i. Animalia
ii. Plantae
iii. Protista (protozoa, microbes)
c. Four-kingdom classification by Herbert F. Copeland
i. Animalia
 ii. Plantae
iii. Protista
iv. Monera —prokaryotes (bacteria and archaea)
d. Five-kingdom classification by Robert H. Whittaker (PYQ)
i. Animalia - multicellular consumers
ii. Plantae - multicellular producers
iii. Protista - unicellular eukaryotes
iv. Monera —prokaryotes (bacteria and archaea)
v. Fungi - multicellular decomposers

e. Six-kingdom and Three Domain classification by Carl Woese

based on their differences in rRNAs

16. Linnaeus’s Classification and Binomial Nomenclature System:

a. Carolus Linnaeus proposed this hierarchical classification system and binomial
nomenclature system to organise and name the organism.
b. He is known as ‘Father of Taxonomy’
c. In binomial nomenclature system, scientific name of each organism consists of two parts
represented with Latin words, first genus and then species
E.g., Homo sapiens
17. Model Organisms:
a. Model organisms serve as a proxy for understanding the biology of humans and human
diseases
b. Model organisms possess unique characteristic features such as easy maintenance in the
lab and short generation times.
c. E.g., mouse and human genomes are ~85% identical; Fruit fly and human are 60%
identical; Yeast has ~23% genes homologs in human.
18. Cell Shape:
a. Shape is related to their function
b. Some cells have dynamic shape
c. The cells may be spherical, oval, rounded or elongated, cuboidal, cylindrical, tubular,
polygonal, plate-like or irregular
19. Three postulates of Cell doctrine or Cell theory:
a. All organisms are composed of one or more cells
b. The cell is the basic unit of life in all living things
c. All cells only arise from pre-existing cells
20. Modern Cell Theory (in addi on to classical cell theory):
a. The cell contains gene c informa on in the form of DNA which is passed on from cell to
cell during cell division.
b. All cells are basically the same in their chemical composi on and metabolic ac vi es.
c. All energy flow of life occurs within the cells -> basic chemical and physiological func ons
such as movement and diges on are carried out inside the cells.
d. The ac vity of cells depends on the ac vi es of sub-cellular structures within it.
21.
22. Animal Cell:

23. Plant Cell:

24. Cell Membrane:

a. Location: forms the outer boundary of the cell
b. Function: Control movement of materials in and out of the cell in addition to enveloping
contents of the cell

25. Fluid-mosaic model of the plasma membrane: (PYQ)

a. Universally accepted model
b. The plasma membrane is a mosaic of components consisting of phospholipids,
cholesterol, and proteins that move freely in the plane of the membrane, which has a
quasi-fluid structure
c. Membranes are dynamic and the components are mobile and capable of interacting with
each other
26. Nucleus:
a. Discovered by Robert Brown
b. The first organelle to be discovered
c. The largest membrane-bound spherical organelle of the cell occupying 10% of its volume
d. Usually, one per cell, except mature RBC (enucleate), slime mould (multinucleate),
paramecium (two nuclei)
e. Stores DNA and controls different activities of the cell such as growth, metabolism,
protein synthesis, and reproduction.
f. Semifluid matrix called ‘nucleoplasm’ harbours chromatin, the condensed form of DNA
g. Membrane-less ‘nucleolus’ synthesise ribosomes

27. Mitochondria:
a. Provides most of the energy (~90%) in the form of ATP that cells need to survive from the
breakdown of food
b. A double membrane-bound organelle with inner and outer membranes separated by an
intermembrane space
c. Inner membrane forms numerous folds termed as ‘cristae’, which extends into the interior
of the organelle termed as the ‘matrix’
d. Matrix contains circular DNA as the genetic material that codes for the genes of enzymes
needed for metabolism of food
 e. Mitochondria regulate Programmed Cell Death (PCD) which is essential for intrauterine
development, removal of damaged or aged cell
f. Mitochondria is involved in storage of calcium ions and generation of heat through
brown fats

37 genes that encode 13 proteins as well as 16S and 12S rRNAs and 22 tRNAs
28. Endoplasmic Reticulum (ER):
a. A series of membrane-lined channels running through the cytoplasm (found in all
eukaryotes except mature RBCs)
b. Acts as a manufacturing unit – production of proteins (RER) & lipids (SER)
c. SER is also involved in the synthesis of steroid hormones, detoxification of drugs and
harmful chemicals in the liver, conversion of glycogen to glucose in the liver, and storage
of calcium ions by sarcoplasmic reticulum in the muscle cells

29. Ribosomes:
a. are non-membrane small spherical organelles (diameter: 23 nm).
b. Comprises of ribosomal RNA (rRNA) plus proteins -> ribonucleoproteins
c. Found in both pro- and eukaryotes
d. Free floating in the cytoplasm or bound to the ER and acts as a protein-making machine
for the cell.
e. Plays a key role in translating the messages encoded within the messenger RNA (mRNA)
transcribed from the gene

f. Each ribosome has two subunits — small and large subunit

 g. 70S ribosomes- prokaryotes 80S ribosomes – eukaryotes
h. Svedberg unit (represented as S or Sv) is a unit for sedimentation rate - a measure of how
quickly a particle sediments from a solution or suspension under the induced
gravitational field of a centrifuge. 80S sediments faster than 70S ribosomes.
i. By Theodor Svedberg, a Swedish chemist
30. Golgi apparatus:
a. Also known as Golgi body or Golgi complex, was discovered by Camillo Golgi in 1898
b. comprise a series of 5–8 cup-shaped, membrane-covered sacs called ‘cisternae’ that look
like a stack of deflated balloons
c. Usually located close to the ER
d. Found in hundreds in some plant cells, whereas animal cells have only few except the
cells which are secretory in function
e. Assists in modifying proteins and lipids synthesised in the ER and prepares to distribute
them outside or to other locations of the cell

31. Vesicle:
a. A small, spherical organelle located within the cytoplasm, which can easily fuse with the
plasma membrane
b. Facilitate bulk transport of large molecules in (endocytosis) and out (exocytosis) of the
cells
c. Are of Five types based on their functions - (PYQ)
i. Transport vesicles: move the molecules such as proteins within the cell between
different locations
ii. Secretory vesicles: excrete materials from the cell: hormones, neurotransmitters,
wastes
iii. Extracellular vesicles: cell-cell communications. E.g., viruses and bacteria interact
with the healthy cells through these.
iv. Lysosomes
v. Peroxisomes
32. Lysosomes:
a. Digestive and garbage disposal system of the cell
What happens to your cells when food is not available to them?
b. They meet their hunger by eating their own components by a process called autophagy
c. This is performed by lysosomes, commonly known as the ‘stomach of the cells
d. Found in all animal cells except RBCs but absent in plants and fungi (function is taken
over by vacuoles)
e. Work as the digestive system of the cell: degrade materials taken up from outside the
cell by endocytosis, and unnecessary waste materials of the cell derived from
phagocytosis and autophagy
f. Phagocytosis: Macrophages ingest and degrade large unwanted particles such as bacteria,
cell debris, and damaged/aged cells. These fuse with lysosomes where their content is
digested by lysosomes.
33. Peroxisomes:
a. Previously known as ‘microbodies’
b. One of its functions is - oxidation of fatty acids producing energy as well as hydrogen
peroxide (which is toxic to the cells), which is then detoxified by an enzyme called
catalase present in the peroxisome itself. That is why it is termed as peroxisomes.
c. Specialized peroxisomes in plant are known as ‘glyoxysomes’ - convert fatty acids and
lipids to sugars in germinating seeds through the glyoxylate cycle
d. Involved in photorespiration of plants.
34. Centriole:
a. Centrioles are found in pairs, positioned right angle to each other and are typically located
near the nucleus in the ‘centrosome’
b. Centrosome is like a courier box within which two centrioles are wrapped along with
some extra proteins
c. Plant cells do not contain centrioles.
d. Plants have a tubulin protein ‘gamma tubulin’ which is used to nucleate microtubules just
like centrioles in animal cells.
e. Helps the cells to divide or make copies of themselves and are only found in animals

35. Chloroplast:
a. A double membrane-bound organelles found in plant cells and eukaryotic algae and
involved in photosynthesis
b. Another internal membrane known as the thylakoid membrane
 c. Thylakoid membrane is extensively folded into small disc-like compartments called
thylakoids which are stacked one upon the other.
d. The stacks of thylakoids are known as grana
e. Thylakoids are surrounded by the innermost matrix or liquid portion, called the stroma 
contains enzymes and the chloroplast genome
f. Thylakoids contain chlorophyll and the ETC for photosynthesis

g. Functions of chloroplast:
i. In plants all the cells participate in plant immune response as they lack specialized
immune cells.
ii. The most important function of chloroplast is to make food by the process of
photosynthesis. Food is prepared in the form of sugars.
iii. During the process of photosynthesis sugar and oxygen are made using light
energy, water, and carbon dioxide.
iv. Light reactions takes place on the membranes of the thylakoids.
v. Chloroplasts, like the mitochondria use the potential energy of the H+ ions or the
hydrogen ion gradient to generate energy in the form of ATP.
vi. The dark reactions also known as the Calvin cycle takes place in the stroma of
chloroplast.
vii. Production of NADPH2 molecules and oxygen as a result of photolysis of water.
viii. By the utilization of assimilatory powers the 6-carbon atom is broken into two
molecules of phosphoglyceric acid.
36. Cell Wall:
a. Cell wall is a tough, rigid layer that surrounds some types of cells.
b. Cell wall is a characteristic feature to cells of plants, bacteria, fungi, algae and some
archaea. It is located outside the cell membrane.
c. The major function of the cell wall is to provide rigidity, tensile strength, structural
support, protection against mechanical stress and infection.
d. Cell wall composition varies from species to species and also depends on the developing
stage of the organism.
i. In bacteria the cell wall is made up of peptidoglycans.
 ii.The Archean cell wall is made of glycoproteins and polysaccharides.
iii.In fungi cell walls are made of glucosamine and chitin.
iv. In algae it is composed of glycoproteins and polysaccharides.
v. The plant cell wall is mainly composed of cellulose, hemicellulose, glycoproteins,
pectins and lignin.
37. Binary Fission:

38. Mitosis:
a. Interphase:
Cells spent most of the time in the interphase before it starts dividing.

b. M-phase:
i. Occurs in somatic cells and essential for growth and repair.
 ii. Four phases: prophase, metaphase, anaphase, and telophase
iii. After chromosome segregation is done, cytoplasm is divided by cytokinesis,
producing two daughter cells.
iv. Otherwise known as ‘equational division’ because the number of chromosomes
and amount of DNA in daughter cells are equal to that of the parent cells.

39. Meiosis:
a. Occurs in the germ cells or reproductive cells
b. Produce four genetically distinct haploid daughter cells
c. Comprises of two successive divisions: Meiosis I and Meiosis II
d. Stages of Meiosis I:
i. Prophase I: Prophase I is the first phase of meiosis I which is longer and complex
than prophase of mitosis. This is subdivided into five sub-stages: Leptotene,
Zygotene, Pachytene, Diplotene, Diakinesis.
ii. Metaphase I: The bivalent chromosomes line up at the equatorial plate and the
microtubules from the opposite poles of the spindle attach to these.
iii. Anaphase I: The homologous chromosomes separate and move to the opposite
ends of the cells, while sister chromatids remain associated at their centromeres.
iv. Telophase I: The nuclear membrane and nucleolus reappear and then cytokinesis
occurs which marks the end of meiosis I. This is called 'dyad of cells'.
40. Discuss the difference between mitosis and meiosis (with diagrams). (PYQ)