ANATOMY OF FLOWERING PLANTS
The branch of botany which deals with study of internal structures and organization of plants or plant organs.
- N. Grew known as father of plant anatomy.
- K.A. Chaudhary known as father of Indian plant anatomy.
Note: The anatomy of seed plants by Katherine Esau was published in 1960.
2. THE TISSUE
- A group of cells which is similar or dissimilar in shape, having a common origin and usually perform a common function is called tissue.
- The term tissue was coined by Nehemiah Grew.
- The tissues are divided into two groups by Karl Nageli :-
A. Meristem Tissues
Growth in plants is largely
- Cell cycle of permanent tissue is restricted to specialised regions of active arrested at G1 stage or it enters in G0 stage cell division called meristem. A meristem so cells, have no capacity to divide. It is a localised region in which actual cell composed of mature cells.
- Meristem term was given by Nageli. It is derived from Greek word meristos (means Divided)
i. Characteristics of Meristematic tissues
- It is an undifferentiated tissue.
- Cell cycle of meristem is in continuous state of division. Thus, meristematic tissue is composed of immaturecells.
- Meristematic cells have only primary cell wall which is thin and flexible (elastic) and made up of cellulose. Secondary cell wall is absent.
- Cells of meristem are small and isodiametric.
- They have dense cytoplasm.
- They have prominent and large nucleus.
- Normally vacuoles are absent in meristematic cells if present then they are small in size and Meristematic cells are metabolically highly active so lack of reserve food in these cells.
- Plastids are absent in meristems. If they are present, then only in the proplastid stage.
- They do not have intercellular spaces. Cells are closely fitted (packed) together. so it is a compact tissue
- Ergastic substances are absent.
ii. Classification of Meristematic Tissue
- MERISTEMATIC TISSUE BASED ON ORIGIN AND DEVELOPMENT
On the basis of origin and development meristems can be divided into following three types:-
(I) PROMERISTEM/EMBRYONIC/MERISTEM/PRIMORDIAL MERISTEM/URMERISTEM
- This meristem develops in beginning during embryonic stage. They develop primary meristem.
i. Primary meristem
- Meristematic cells developed from promeristem are known as primary meristem.
- These cells are always in division phase and form primary permanent tissue.
ii. Secondary Meristem
- These are the meristems developed from primary permanent tissues.
- Some of the cells of primary permanent tissues become meristematic and constitute secondary meristem.
- By the activity of secondary meristems, secondary growth takes place.
Note: Formation of meristem from any permanent tissue is called dedifferentiation
B. MERISTEMATIC TISSUES BASED ON LOCATION (POSITION) IN PLANT BODY
On the basis of position, meristematic tissues are divided into three types:-
a. Apical Meristem
The meristems which occur at the tips of roots and shoots and produce primary tissues are called apical meristems. They are responsible for increase in the length of plant organs. Example: - Root apex, shoot apex. They are responsible for primary growth.
Note: In embryonic stage, apex has two regions
- Eumeristem is derived from promeristem.
According to Haberlandt, eumeristem (It is a primary meristem) is divided into three regions on the basis of function.
- Protoderm: It is the outer most layer of eumeristem. By the activity of protoderm epidermal tissue system is formed. It includes epidermis, root hair, stem hair etc.
- Procambium: These cells are long and it gives rise to the vascular tissue system. It includes Xylem, phloem.
- Ground Meristem: The cells of this region are large, thin walled and isodiametric. Ground tissue system is formed by the activity of these cells. It includes hypodermis, cortex, endodermis, pericycle, pith-rays and pith.
b. Intercalary Meristem:
- The meristem which occurs between mature tissues.
- This is the separated region of apical meristem.
- By the activity of this meristem length of the plant organs increases.
- They are present in some plants stem.
- They may be present either at the base of internode e.g. grasses, bamboo and Equisetum etc., or at the base of node e.g. Mint. They are also present at the base of leaves e.g. Pinus. By the activity of this meristem, length of leaves increases.
Note: They are short lived and convert into permanent tissue.
- Both apical meristem & intercalary meristems are primary meristem because they appear early in the life of a plant and contribute to the formation of primary plant body.
c. Lateral Meristem:
- Lateral meristem occurs in lateral side of plant organ or parallel to the longitudinal axis /Tangential plane of plant organ.
- Activity of lateral meristem increases the girth of plant organ.
- Lateral meristems are both primary and secondary in origin (mostly secondary in origin).
- Primary lateral meristem :
1. Marginal meristem
2. Intra fascicular cambium
1. Marginal meristem: - It occurs at the margin of leaf. Its activity increases the width of leaf.
2. Intra fascicular cambium or fascicular cambium:
This cambium occurs inside the vascular bundle. Except intra fascicular cambium all cambia are secondary in origin.
To continue its own race, an organism by the process of reproduction, produces offsprings like its own. In sexual reproduction the organisms produce male and female gametes which on combining, develop into a new individual. The formation of gametes takes place in the reproductive organs
- Embryology is the branch of biology which deals with the study of all those processes, which take place during development of foetus.
A. Primary sex organ
- Essential organs which form the gametes. In males, the gamete forming organs are the testes. In females, the corresponding organs are ovaries
- The male gametes is spermatozoon. The female gamete is ovum.
B. Secondary sex organ
- These organs form the passage for the gametes to help the union of male & female gametes.
- In male these include epididymis, vas deferens, seminal vesicles, prostate, bulbourethral glands & penis. In female these organs are fallopian tube, uterus and vagina.
Development of Sex organ:
- During intra uterine life (IUL) testis & ovary develop from mesoderm. They develop in abdominal cavity. At the time of birth, testes descend down into scrotal sac but ovaries remain in abdominal cavity,
2. THE MALE REPRODUCTIVE SYSTEM
- Scrotal Sac & Testes
- In man, one pair testes are the main or primary reproductive organ. Size 4-5 cm × 2-3 cm
- Both testes are located in a small bag like structure situated below & out side the abdominal cavity called as scrotum or scrotal sac. The temperature of scrotum is 2 to 2.5 lesser than body temperature.
- Internally scrotum is lined by dartos muscle & spermatic fascia.
- Dartos muscle helps in regulation of the temperature with in the scrotum during cold season,
- It becomes contracted in cold & during warm season, it becomes relaxed.
- Cremaster muscles line inside the wall of scrotal & inguinal canal region and help in elevation of testes.
- Each testis is attached to the walls of the scrotal-sac through flexible, elastic fibres. This group of fibres is called Gubernaculum or Mesorchium.
- Each testis is attached to the dorsal body wall of the abdominal-cavity through a cord termed as the Spermatic-cord. This cord is made up of elastin fibres & spermatic fascia. The contents of cord are vas deferens, gonadial veins, gonadial arteries, nerves and lymphatics.
During embryonic stage, testes develop in abdominal cavity & they descend to reach the scrotum at the time of birth.
When the testes does not descend to reach the scrotum but remain in abdominal cavity at the time of birth this conditions is called undescended testes or cryptorchidism. Such testis cannot develop and function properly and may develop malignancy.
Orchiopexy: When the undescended testes are brought into scrotal sac by surgical process during childhood this process called as orchiopexy.
Castration: Crushing of testes in bulls to convert them to bullocks. (This makes than more obidient due to fall in the level of testosterone)
- Each scrotum is connected to the abdominal cavity through a passage termed as inguinal-canal. Through this canal the testis descend down into the scrotalsacs at the time of birth.
- Spermatic cord in males passes through the inguinal canal.
- Sometimes the inguinal canal may tear leading to abnormal protrusion of abdominal contents like loops of intestine into the inguinal canal. This condition is called as inguinal hernia.
B. Internal Structure of Testis
- Testis is covered by three coats. Outer most is tunica vaginalis. Middle coat is tunica albuginea & inner mostis tunica vasculosa.
- Tunica vaginalis has a parietal & visceral layer. It covers the whole testis except it's posterior border from where the testicular vessels & nerves enter the testis.
- The Tunica albuginea is a dense, white fibrous coat covering the testis all around. The posterior border tunica albuginea is thickened to form vertical septum called the Mediastinum testis.
- Tunica vasculosa is the inner most vascular coat of the testis lining testicular lobules.
REPRODUCTION IN ORGANISMS
REPRODUCTION: - Reproduction is the ability of living organism to produce a new generation of living individuals similar to themselves.
Basic features of reproduction: - All organisms reproduce. Modes of reproduction vary in different organisms. However, all modes have certain common basic features. These are
- Replication of DNA. This is the molecular basis of reproduction.
- Cell division, only mitotic, or both mitotic and meiotic. This is cytological basis of reproduction.
- Formation of reproductive bodies or units.
- Development of reproductive bodies into offspring.
Types of reproduction: - These are of two main types
(1) Asexual (Non-gametic) (2) Sexual (gametic)
2. TYPES OF REPRODUCTION
- Asexual reproduction /Vegetative Reproduction /Propagation
- Plants belonging to this category propagate by a part of their body other than a seed. The structural unit that is employed in place of seed for the propagation of new plants is called propagule. In Angiosperms any parts of the plants - roots, stems and leaves used for vegetative propagation.
- Generally method of vegetative propogation have been further divided into two types-
I. Natural vegetative propagation
- By roots: - Modified tuberous root of Sweet potato (Ipomoea batatas), Asparagus, Tapioca, Yam, Dahlia and Tinospora can be propagated vegetatively when planted in soil.
- In some plants adventitious buds develop on the ordinary roots like-Dalbergia sisso, Populus, Guava, Murraya, Albizzia lebbek etc. which grow to form new plants.
- The buds present on the roots grow into leafy shoot above the ground is called Slips.
b. Underground Stem: - In some plants underground modified stem such as -
- Rhizomes - Typha; Canna, Ginger, Turmeric, Lotus, Musa etc.
- Corm - Gladiolus, Colocasia, Crocus, Amorphophallus, Alocasia etc.
- Bulbs - Onion, Garlic and Lilies
- Tubers - Potato, Helianthus tuberosus etc. which grow to form a new plants.
- Reproductive Health -
- According to the World Health Organisation (WHO), reproductive health means a total wellbeing in all aspects of reproduction, i.e., physical, emotional, behavioural and social.
- Family planning refers to practices that help individual to attain certain objectives
- To avoid unwanted births
- To bring about wanted birth
- To regulate the interval between pregnancies
- To determine the number of children in family India is first country in world to intiate family planning in 1951. In 1977 it changed into family welfare programme “To improve the quality of life of people. “ “ Reproduction and child health care (RCH) programmes”
Small Family norm
1970 Slogan was -“Do ya Teen Bas”
1880 Slogan was” -“Sons or Daughter-Two will do”
-“Second after 3 years”
2. REPRODUCTIVE HEALTH
What is Reproductive Health?
The term reproductive health simply refers to healthy reproductive organs with normal functions. But according to the World Health Organisation (WHO) reproductive health means a total well being in physical, emotional, social and behavioural aspects in reproduction. Thus reproductive healthy persons heave physically and functionally normal reproductive organs and normal behavioural and emotional interactions among them in all sex-related aspects. Now the question arises why it is so significant to maintain reproductive health and what are the methods to achive it?
- Over Population. Main problem of India is its excess population.
- Early Marriage. Children are often married as soon as they attain puberty.
- Health of Mothers. Early marriage leads to several diseases in mothers.
- Deformities. Deformities are common in children of early marriage.
- Maternal Mortality Rate (MMR) and infant Mortality Rate (IMR). These are high in early marriage
- Sexually Transmited Diseases (STDs). The children who have married early, they do not have proper knowledge of reproductive organs, hence the STDs are common in these persons
- Career. Early marriage blocks the career of the couple especially of the lady.
- Family Planning Programme. It was invented in 1951.
- Awarness about Reproduction. Audio-visual and print media, governmental and non-governmental agencies are doing good job to create awareness among people about reproduction in humans. Parents, close relatives, friends and teachers also have a major role in giving the above information.
- Sex Education. Sex education in schools should also be introduced and encouraged to provide right information about myths and misconceptions about sex-related aspects.
- Knowledge of growth of reproductive organs and STDs. Proper information about reproductive organs, adolescence (period of rapid growth between childhood and adulthood), safe and hygienic sexual practices, sexually transmitted diseases (STDs), e.g., AIDS etc., would help to lead a reproductive healthy life.
- Birth control devices and care of mother and child. Fertile couples and people of marriageable age group should know about available birth control devices, care of pregnant mothers, postnatal (after birth) care of the mother and child, importance of breast feeding, equal importance for the male and female child, etc.
- Prevention of Sex abuse and sex related crime. Awarness of problems due to uncontrolled population growth, social evils like sex abuse and sexrelated crime, etc. need to be created so that people should think and take up necessary steps to prevent them and thereby build up a reproductive healthy society.
- Information about reproduction related problems. For successful action plans to attain reproductive health requires good infra structural facilities, professional expert knowledge and material support. These are necessary to provide medical help and care for reproduction related problems like menstrual problem, infertility, pregnancy, delivery, contraception, abortions, sexually transmitted diseases (STDs). Implementation of better techniques and new strategies are also required to provide better care and help to people for reproductive health.
- Research in reproductive health area. It should be encouraged and supported to find out new method. "Saheli" a new oral contraaceptive for the females was developed by our scientists at Central Drug Research Institute (CDRI) in Lucknow, India.
- Medical Facilities. Better awareness about sex related problems, prenatal care of mother, medically assisted deliveries and post natal care of mother and infant decrease maternal and infant mortality, small families better dection and cure of sexually transmitted diseases (STDs) and increased medical facilities for sex-related problems, etc. indicate improved reproductive health of male and female individuals and children.
- Amniocentesis-Meaning and Use. Amniocentesis is a foetal sex determination and disorder test based on the chromosomal pattern in the amniotic fluid surrounding the developing embryo.
Procedure. Amniotic fluid contains cells from the skin of the foetus and other sources. These cells can be used to determine the sex of the infant, to identify some abnormalities in the number of chromosomes and to detect certain biochemicals and enzymatic abnormalities. If it is established that the child is likely to suffer from a serious incurable congenital defect, the mother should get the foetus aborted.
Misuse of Amniocentesis. It is being used to kill the normal female foetus. It is legally banned for the determination of sex to avoid female foeticide.
3. BIRTH CONTROL
Birth control methods act by preventing any one or more of the three major steps in the reproductive process.
- Preventing sperm transport to the ovum.
- Preventing ovulation and
- Preventing implantation of early embryo in the uterus.
Temporary methods of birth control
- Natural Methods. These methods avoid meeting sperm and ovum
(a) Rhythm or Periodic abstinence method - Ist 7 days after Menstruation Cycle (M.C.) and 7 days before M.C. is called safe period because in these 14 days ovum is absent in fallopian tubes.. Hence fertilization usually does not occur.
RESPIRATION IN PLANTS
- DO PLANT BREATHE?
- Respiration is a Amphibolic & exergonic cellular process.
- Respiration is an enzymatic process, which is also known as internal respiration / tissue respiration/ dark respiration / cellular respiration / mitochondrial Respiration.
- An important feature of respiration is liberation of metabolic energy as ATP.
- Respiratory substrate:
- (Carbohydrates → Fats → Protein → others)
- When respiratory substrates are carbohydrates like glycogen, starch, sucrose, hexose or fats, then respiration is known as floating respiration.
- When protein is oxidised in respiration, then respiration is known as protoplasmic respiration protoplasmic components or cellular proteins may oxidised at the time of starvation & disease.
- Exceptionally oxidation of proteins in legume seeds is called floating respiration.
Types of respiration:
- Aerobic respiration: - The complete oxidation of food with the use of oxygen and when entire carbon released, as CO2 is called as aerobic respiration.
B. Anaerobic respiration: - This is an incomplete oxidation.
- When food is oxidized into alcohol or organic acids without use of oxygen.
During it most of the energy is lost in form of heat. It occurs in cytoplasm and only 2ATP are produced
- Anaerobic respiraton was first reported by Kostytchev.
- Anaerobic respiration may takes place in bacteria, some lower parasitic animals (Ascaris, Taenia) plants, RBCs. & muscles of human body. When oxygen is not available, then food is incompletelyoxidised in to some organic compounds like ethanol, acetic acid, lactic acid.
- In muscle cells & some bacteria, the energy is produced by breaking of glucose into lactic acid inside the cells.
- The amount of energy released in anaerobic respiration is much less than aerobic respiration.
- Fermentation is performed by only some fungi & some bacteria (only by microbes) and is an extracellular process. No ATP is produced. If occure inside the cell then 2ATP forms
In energy generating processes either inorganic or organic compounds function as electron acceptors.
The terms aerobic respiration, anaerobic respiration and fermentation are often used on energy generating processes.
- In aerobic respiration the final electron acceptor is free O2.
- In anaerobic respiration the final electron acceptors is organic compound or inorganic compounds (nitrates) other than free O2
- In fermentation, the final electron acceptor is organic intermediates of the process, no external substance.
- Both anaerobic respiration and fermentation are incomplete oxidations.
- Inhibitory effect on respiration high conc. of oxygen is called Pasteur Effect.
2. AEROBIC RESPIRATION STEPS OF RESPIRATION
- Glycolysis – Occurs in cytosol/cytoplasm
- Formation of Acetyl COA – (Link Reaction)
Perimitochondrial space (outer chamber)
- TCA cycle or Kreb's cycle – Matrix of mitochondria & cytosol in bacteria
- ETS – Occurs in cristae or inner memberane of mitochondria and Oxidative phosphorylation –Occurs in Oxysome head (F1 particle)
- Glycolysis – EMP – (Embden, Meyerhof, parnas) pathway.
- The glycolysis is common phase for aerobic & anaerobic respirations both.
- Glycolysis involves a series of ten biochemical reactions in cytoplasm.
- In glycolysis, neither consumption of oxygen nor liberation of CO2 take place.
- In glycolysis, 1 glucose, produces 2mol. of pyruvic acids (3C)
- 2NADH2 & 2ATP are generated in glycolysis, which are equal to 8 ATP.
- Substrate level phosphorylation forms 4 ATP :-
[When the substrate releases energy for phosphorylation of ADP OR formation of ATP, without ETS then called as substrate level phosphorylation]
- Glycolysis is also known as oxidative anabolism or catabolic resynthesis, because it links with anabolism of fats and amino acids. An intermediate PGAL is used for the synthesis of glycerol later forms fats or lipid. PGA is used for synthesis of Serine, Glycine, Cystine. Alanine forms from pyruvate.
- 1, 3, 10 are irrev. Reaction in EMP pathway
Biochemical reactions of Glycolysis
- Phosphofructokinase is an allosteric enzyme. The phosphorylation of fructose 6 phosphate is the most important regulation point of glycolysis.
- Phosphofructokinase has multiple allosteric modulator. It's activity is inhibited by ATP (–ve modulator) and stimulated by ADP & AMP (+ve modulator). Most of the biochemical reactions catalysed by allosteric enzymes are irreversible type and these are control point of glycolysis.
B. Formation of Acetyl-Co-A:-(Link/Gateway reaction)
- When respiration is aerobic, then pyruvic acid is oxidised to form 2C compound - Acetyl Co-A. It occurs in presence of O2 and CO2 is released first time during it.
- Acetyl Co-A is a connecting link between glycolysis & Krebs-cycle. Decarboxylation and dehydrogenation (Oxidative decarboxylation) take place during formation of acetyl Co-A.
- Acetyl Co-A is formed in perimitochondrial space by enzyme pyruvate dehydrogenase complex.(Mg++, LA (Lipoic Acid), TPP(Thiamine pyrophosphate), NAD, CoA)
SEXUAL REPRODUCTION IN FLOWERING PLANTS
- INTRODUCTION OF FLOWER
C.F.Wolf - Father of plant Embryology.
- Prof. P. Maheshwari - Father of Indian plant Embryology. He wrote a book - 'An Introduction to Embryology of Angiosperms'.
- According by Goethe, Flower is modified shoot which shows favourable adaptation for reproduction through a special method. Flower has a small or long stalk like – structure called pedicel. Free end of the pedicel is flattaned or dome shaped is called thalamus. The thalamus is a type of modified stem, on which nodes and internodes are present.
- Nodes are present very close to each other and internodes are small highly reduced in the thalamus.
- The whorls present in the flower are the modifications of leaves and arranged in four circles on the thalamus.
- The four nodes are present on the thalamus, in which first modified leaves are attached on the first lower node are called calyx.
- The corolla born on the second node. Androecium are present on the third node and gynoecium on the fourth node in uppermost position.
- In some of the plants the length of internode increases which is present in between Calyx and Corolla is called Anthophore e.g. Silene plant, Dianthus.
- The length of internode between the corolla and androecium increases. It is called androphore e.g. Passiflora.
- If the internode between androecium and gynoecium increases then it is called gynophore. e.g. Capparis.
- Both androphore and gynophore are present in the same flower is called gynandrophore or androgynophore.
E.g. Gynandropsis pentaphylla and Cleome gynandra.
- Calyx is also modified vegetative leaves. Such as in Mussaenda flower, one sepals of calyx modified into leaf like bright and attractive yellow colour structure called "Advertising flag". It helps in pollination
- In some flowers; thalamus grows inside the ovary is called carpophore
- e.g. Coriandrum and Foeniculum
- In Nymphaea Petals like stamens are present.
- On the basis of above examples, we can prove "Flower is modified shoot".
- The plants in which flowering and fruiting takes place only once in the whole life cycle are called monocarpic e.g. Annual & Biennial plants.
- The plants in which flowering and fruiting takes place many times in the entire life cycle are known as polycarpic e.g. Perennial plant.
- Bamboo, Palms, Banana, Centuary plant (Agave Americana) are perennial plants but they are the example of monocarpic plants.
2. PRE-FERTILISATION – STRUCTURE & EVENTS
- "Reproduction is one of the important processes by which every living organism make a copy of itself. It is the means of multiplication and perpetuation of species because the older individual of each species undergo senescence and die" All the reproductive methods of plants are broadly categorized into two types –
- Sextual Reproduction
- Asexual Reproduction
- In Angiosperms male and female gametes are formed in male and female sex organs by the process of meiosis. Both the gametes fuse together to form a diploid zygote which gives rise embryo. The process in which embryo is formed by meiosis and fertilization is called Amphimixis.
- Male Reproductive Organ's –Androecium / Stamen / Microsporangium / Pollen grain
- Male reproductive organ is called androecium and their unit is called stamen. Stamen is also known as microsporophyll. There are 6 stamens in Capsella. A typical stamen is differentiates into three parts -along, thin structure is called filament which joins the stamen to the thalamus. The free end of the filament, a swollen spore bearing structure is called anther. Anther and filament are attached together with help of small region, called connective. Connective contains vascular tissues. The main parts of the stamen is the anther.
- Each anther generally bilobed structure i.e., anther has two anther lobes is called dithecous.
- Each lobe of anther has two chambers which are called pollen sacs or pollen chambers.
- Therefore, a typical anther has four pollen sacs is called tetrasporangiate.