A flower that does not have a stalk and is directly attached to the stem is called a sessile flower.
Definitions [16]
Definition: Lifespan
Lifespan is the duration or period from birth to the natural death of an organism.
Definition: Reproduction
Reproduction is the process of formation of new individuals by sexual or asexual means, which can repeat the process in their own turn.
or
Formation of new organism of same species by earlier existing organism is called as reproduction.
or
Reproduction is a biological process that results in the formation of new individuals of the same kind, though usually with slight genetic, structural and physiological variations.
Definition: Bisexual Flower
A flower that has both androecium (male part) and gynoecium (female part) in the same flower is called a bisexual flower.
Example: Hibiscus
Define.
Inflorescence
A specialised axis or branch over which flowers are produced or borne in definite manner is known as inflorescence.
Definition: Pedicellate Flower
A flower that has a stalk called pedicel for support is called a pedicellate flower.
Definition: Sessile Flower
Definition: Unisexual Flower
A flower that has only one reproductive whorl (either androecium or gynoecium) is called a unisexual flower.
- If it has only androecium: male flower
- If it has only gynoecium: female flower
Example: Papaya
Definition: Pollination
Transfer of pollen grains from the anther to the stigma of a flower is called pollination.
or
Pollination is the transfer of pollen grains from the anther of a flower to the stigma of the same flower or of another flower of usually the same species.
Definition: Self-pollination
When pollination occurs within the same flower or between two flowers on the same plant, it is called self-pollination.
or
Transfer of pollen grains from the anther to the stigma of the same flower or another flower on the same plant is said to be self~pollination.
Define Pollination.
Transfer of pollen grains from the anther to stigma is called pollination.
Definition: Cross-pollination
When pollination occurs between flowers on two different plants of the same species, it is called cross-pollination.
or
Transfer of pollen grains from the anther of a flower from one plant to the stigma of the flower on another plant is called cross-pollination
Define: Menarche
It is the stage when a girl menstruates for the first time.
Define ovulation.
The release of the ovum from the ovary is called ovulation.
Definition: Menstrual Cycle
The rhythmic series of changes in the sex organs throughout the reproductive life of a female primate (e.g., monkeys, apes, and human beings) from puberty to menopause is called the menstrual cycle (L. mensis = month, lunar month).
Definition: Reproductive Health
Reproductive health is defined as a state of complete physical, emotional, behavioural, and social well-being in all matters related to the reproductive system and its functions, and not merely the absence of disease or infirmity.
Define amniocentesis.
It is a technique in which amniotic fluid is withdrawn from the uterus of a pregnant lady and the amniotic cells are cultured and studied for cytological observations to determine any chromosomal abnormalities.
Key Points
Key Points: Reproduction
- Meaning - Reproduction is the production of young ones similar to their parents. It is an essential biological process for the continuation of the species and continuity of life.
- Lifespan = period from birth to natural death; ranges from 1 day (Mayfly) to 3,000–4,000 years (Sequoia).
- Two Types - All methods of reproduction fall into two categories: Asexual Reproduction and Sexual Reproduction.
- Single-celled organisms (Amoeba, Bacteria) do not undergo natural death — they divide by binary fission.
- Four life stages: Juvenile → Reproductive → Senescent → Death.
- In plants, the reproductive phase begins at flowering.
- Monocarpic plants flower once; Polycarpic plants flower every season.
- Asexual reproduction = one parent, clones produced, faster.
- Sexual reproduction = two parents, gametes, zygote formed, genetic variation.
- The three phases of sexual reproduction: Pre-fertilisation → Fertilisation → Post-fertilisation.
Key Points: Sexual Reproduction in Plants
- Sexual reproduction involves the fusion of male and female gametes from two parents to form a diploid zygote.
- A flower is the reproductive structure in plants that produces gametes and enables fertilisation.
- A flower has four whorls: calyx, corolla, androecium (male), and gynoecium (female).
- It includes meiosis for gamete formation and fertilisation, producing genetically different offspring.
- Sexual reproduction occurs in three stages: pre-fertilisation, fertilisation, and post-fertilisation.
Agencies of Pollination
| Agency | Agent | Type | Examples |
|---|---|---|---|
| Anemophily | Wind | Abiotic | Wheat, rice, maize, grass |
| Hydrophily (Hypo) | Water (submerged) | Abiotic | Zostera |
| Hydrophily (Epi) | Water (surface) | Abiotic | Vallisneria |
| Entomophily | Insects (e.g., bumblebee) | Biotic | Rose, Jasmine, Salvia, Lotus |
| Ornithophily | Birds (e.g., sunbird) | Biotic | Bombax, Butea, Callistemon |
| Chiropterophily | Bats | Biotic | Anthocephalus, Kigelia, Adansonia |
Key Points: Pollination
- Pollination is the transfer of pollen grains from anther to stigma and is essential for fertilisation since gametes are non-motile.
- Pollination occurs through external agents such as wind, water, and animals because pollen grains cannot move on their own.
- There are three types of pollination: autogamy (same flower), geitonogamy (same plant), and xenogamy (different plants of the same species).
- Self-pollination leads to inbreeding, while cross-pollination increases genetic variation.
- Abiotic agents of pollination include wind (anemophily) and water (hydrophily).
- Biotic agents include insects, birds, and bats, which help in effective pollen transfer between flowers.
Key Points: Cross-pollination
- Cross-pollination is the transfer of pollen grains from the anther of one plant to the stigma of another plant of the same species.
- It is also known as Allogamy, while Xenogamy refers specifically to pollination between different plants.
- Cross-pollination usually occurs with the help of external agents such as wind, water, insects, birds, and animals.
- This type of pollination produces genetically varied, healthier, and more adaptable offspring.
- Cross-pollination helps in the development of new plant varieties and improves crop quality and vigour.
- It requires the production of a large number of pollen grains, leading to wastage and dependence on pollinating agents.
Key Points: Menstrual Cycle (Ovarian Cycle)
- The menstrual cycle is a series of monthly changes in females of reproductive age.
- The beginning of the cycle is called menarche, and its permanent stop is called menopause (around 45–50 years).
- It occurs mainly in primates, including humans, and involves changes in the ovaries and uterus.
- The cycle is controlled by hormones (gonadotropins and ovarian hormones) and repeats every ~28 days.
- In the middle of the cycle, ovulation occurs, where an egg is released from one of the ovaries.
Key Points: Reproductive Health
- Reproductive health, as defined by WHO, refers to complete physical, emotional, behavioural, and social well-being in all aspects related to reproduction.
- India’s Reproductive and Child Health (RCH) programmes aim to promote reproductive health through family planning, maternal and child care, awareness creation, and access to medical facilities.
- Education and awareness, including sex education for adolescents, help prevent myths, sexually transmitted diseases (STDs), unsafe practices, and promote hygienic and responsible sexual behaviour.
- Preventive measures such as menstrual hygiene, genital cleanliness, planned parenthood, immunisation, and statutory bans on sex determination are essential for a healthy society.
- Sexually transmitted diseases like syphilis and gonorrhoea adversely affect reproductive health, highlighting the need for early diagnosis, treatment, and improved medical infrastructure.
