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Ideas to cover


  • Plant Hormones
  • Plant Reproductive System
  • Immunity in humans
  • Immunization in India

Plant Hormones


  • Plants lack a “proper” nervous system and Endocrine system
  • There are no specific glands (like in animals)
  • Individual plant cell is capable of producing plant hormones
  • Also called -> Phytohormones
  • They affect which tissues grow upward and which grow downward, leaf formation and stem growth, fruit development and ripening, plant longevity, and even plant death


Major Plant Hormones


  • Auxins:

– 1st phytohormone discovered (by Charles Darwin)

– positively influence cell enlargement, bud formation and root initiation

– Cause for Phototropism, Apical Dominance, development of fruit

– Functions:

  • Promote flowering
  • Development of roots in certain propagated plants
  • Herbicide/weedicide [some auxins are toxic in higher concentrations]
  • Prevent dropping of fruit and leaves at early stages
  • Induction of “parthenocarpy” (fruit induction without fertilization) forming seedless fruits


Major Plant Hormones


  • Cytokinins (CKs)

– Influence cell division and shoot formation

– help delay senescence of tissues

– mediating auxin transport throughout the plant, and affect internodal length and leaf growth

– Counter Apical dominance with lateral dominance and bud growth

– Promote abscission of leaves, flower parts, and fruits

– Used in tissue culture to induce cell division in mature tissues

– Keep flower fresher for longer time


Major Plant Hormones


  • Gibberellins (GAs)

– Acidic in nature

– Delay senescence in fruits

– Needed for Germination -> break bud and seed dormancy

– Cell elongation -> Help fruits like apples to elongate and improve their shape

– Used as the spraying agent to increase sugarcane yield by lengthening of the stem


Major Plant Hormones


  • Abscisic Acid (ABA) – Growth inhibitor

– preventing the sprouting activities in seeds and buds

– Induces seed dormancy and prevents germination

– Aids stomatal closing reduce transpiration rate

– “Stress hormone”

– as aids in countering some stresses (e.g. water stress)


Major Plant Hormones


  • Ethylene

– Synthesized by ripening fruits and ageing tissues

– affects cell growth and cell shape; when a growing shoot hits an obstacle while underground, ethylene production greatly           increases, preventing cell elongation and causing the stem to swell

– stems of trees are subjected to wind, causing lateral stress, greater ethylene production occurs, resulting in thicker,                      more sturdy tree trunks and branches

– Main use -> fruit ripening

– Promotes sprouting of tubers


Plant Reproduction


  • Reproduction: production of offspring
  • 2 modes:

– Asexual – no fusion of male and female gametes

– Sexual – seed formation from fusion of male and female gametes

  • Asexual reproduction can be through various methods in various organisms:

– Fission (unicellular organism) -> division of cell into two or more daughter cells identical to the parent cell

  • Binary fission
  • Multiple fission

– Budding: formation of small bulge near cell into which the cytoplasm and nucleus pass e.g. in yeasts, Hydra, flatworms      and tapeworms

– Sporing

– Fragmentation -> breaking of organism into two or more parts followed by regenetaion


Plant Reproduction



Plant Reproduction


  • Vegetative Propagation:

– Roots/stems/leaves= vegetative parts of a plant

– Regenerative reproduction where new plant is produced from existing vegetative parts

– Genetically identical to the parent

– Leaves of some plants produce plantlets at leaf notches e.g. in bryophyllum

– Strawberry plant has runners running parallel and close to the ground -> where they touch the ground they develop root        and shoot system

– Vegetative propagation also involves few specialized organs that develop during the process e.g. bulbs, corms, tubers,          rhizomes etc.


Plant Reproduction



Plant Reproduction


  • Artificial vegetative propagation:

– The regenerative properties of plants used to create identical plants

– Cuttage: use of cuttings -> mainly stems which are then placed in water/moist soil and grows into complete plant

– Grafting: Cutting part of plant (scion) and grafting (attaching) it to another plant (called stock) -> the stock acts as root             system and lower part of new plant

– Layering:

  • Mound layering/ground layering
  • Air Layering

– Tissue culture: plant cells are taken from various parts of the plant and are cultured and nurtured in a sterilized                        container. The mass of developed tissue, known as the callus, is then cultured in a hormone-ladened medium and                   eventually develops into plantlets which are then planted and eventually develop into grown plants.


Plant Reproduction





Plant Reproduction


  • Sexual reproduction in plants

– Involves formation of male and female gametes

– Flower is the reproductive part of angiosperms

– It consists of 4 parts:

  • Petals • Sepals
  • Stamen (male reproductive part)

– Anther

– Filament

  • Pistil/carpel (Female reproductive part)

– Stigma

– Style

– Ovary

– A flower may consist of either stamen or pistil or both. Based on this, a flower can be either unisexual or bisexual. A              bisexual flower is composed of all the four parts mentioned above, e.g. Rose, China rose. Whereas, plants like papaya              and  cucumber produce only unisexual flowers.


Plant Reproduction


Plant Reproduction


  • In order for formation of zygote -> male gametes need to fertilize female gametes
  • The process of transferring of pollen grains from anther to the stigma is called “pollination”
  • Pollination can be of 2 types:

– Self pollination -> anther and stigma of same flower (autogamy), or flower on the same plant (geitonogamy)

– Cross Pollination -> pollen from one plant transferred to stigma of another plant

  • Pollination done by pollinating agents e.g. winds, insects, bees, birds, artificial (by humans) etc.


Plant Reproduction


  • Fertilization:

– Fusion of male and female gametes

– Pollen to stigma -> stigma releases sugar solution to feed pollen cells

– A pollen tube emerges from one of the poles in the wall of pollen grain and extends downwards in the style (feeding on          style tissue)

– Reaches the embryo sac in ovule releasing the male gametes (each pollen has 2 male gametes)

– One male nucleus fuses with female gamete forming diploid nucleus and other male gamete fuses with normal nucleus          forming a triploid nucleus -> leading to formation of 2 structures in seeds -> embryo and endosperm

– Further division of diploid embryo produces seeds in ovary – Surrounding ovary is transformed into fruits


Plant Reproduction


  • Germination:

– Sprouting of the seed which follows the seed dormancy period


Immunity in humans


  • State of resistance of an organism to invading biotic or abiotic pathogens and their harmful effects that prevents the development of infection


Innate/Inborn                                                                                                                                                Acquired/Adaptive


Immunity in humans


  • Innate/Inborn:

– Native immunity

– exists by virtue of an organisms constitution, that is its genetic make-up, without an external stimulation or a previous                infection

– E.g. Presence of skin, presence of basic WBCs

– neutrophils for phagocytosis, Inflammation etc.

  • Adaptive/Acquired:

– A type of Specific Immune System

– Learnt during lifetime

– creates immunological memory after an initial response to a specific pathogen, and leads to an enhanced response to               subsequent encounters with that pathogen

– Invovles the role of lymphocytes in form of B and T cells

– Has both humoral and cell mediated components


Immunity in humans


Acquired Immunity

Active                                                                                                                                                                           Passive


  • Active Immunity: Develops in response to infection of vaccination

– lasts long-term, sometimes lifelong

  • Passive Immunity: Develops in response to external antibodies

– short lived—usually lasting only a few months


Immunity in humans


Immunity in humans


  • Immunization:

– process by which an individual’s immune system becomes fortified against an agent

– Non-Self molecules -> triggers immune response + forms immunological memory

– The formation of memory B and memory T cells allow swift second response

  • Natural Active immunity formation can be dangerous that is why artificial active immunization is preferred through “vaccinations”



Immunity in Humans


  • Vaccinations:

– Administration of vaccine • Vaccine:

– contain a microorganism or virus in a weakened or killed state, or proteins or toxins from the organism

  • Major types:

– Killed or Inactivated

– Live attenuated

– Subunit vaccines

– contain only pieces of pathogen they protect against

  • E.g. toxoid, conjugate, recombinant vaccines


Immunity in Humans


  • Immunization Programme in India:

– introduced in 1978 as ‘Expanded Programme of Immunization’ (EPI) by the Ministry of Health and Family Welfare,                  Government of India.

– In 1985, the programme was modified as ‘Universal Immunization Programme’ (UIP) to be implemented in phased                   manner to cover all districts in the country by 1989-90 with the one of largest health programme in the world.

– Ministry of Health and Family Welfare, Government of India provides several vaccines to infants, children and pregnant             women through the Universal Immunisation Programme.

– UIP become a part of Child Survival and Safe Motherhood Programme in 1992 • Mission Indradhanush:

– it was seen that the increase in immunization coverage had slowed down and it increased at the rate of 1% per year         between 2009 and 2013.

– 2014 -> MI -> aim of expanding immunization coverage to all children across India by year 2020

– 7 vaccination: Diphtheria, Pertussis, Tetanus, Childhood Tuberculosis, Polio, Hepatitis B and Measles

  • Later: rotavirus, Japanese Encephalitis (JE) and Hemophilius influenzae type B, rubella, penumonia, meningitis vaccines also added


Immunity in Humans


– It is a nationwide initiative with a special focus on 201 high focus districts. These districts accounted for nearly 50% of                the total partially vaccinated or unvaccinated children in the country.

– The rate of increase in full immunization coverage increased to 6.7% per year through the first two phases of ‘Mission               Indradhanush’.

  • Intensified Mission Indradhanush: – 2017

– Target: very child under two years of age and all those pregnant women who have been left uncovered under the routine            immunisation programme. The special drive will focus on improving immunization coverage in select districts and cities              to ensure full immunization to more than 90% by December 2018.

– Areas: high priority districts + urban areas • IMI 2.0:

– Dec 2019 to March 2020

– Enhanced immunization session with flexible timing, mobile session & mobilization by other departments

– Enhanced focus on left outs, dropouts, and resistant families & hard to reach areas

– Focus on urban, underserved population and tribal areas