Cell Division and Asexual Reproduction

Cell Division

• Asexual reproduction produces offspring that are genetically identical to the parent.
• This is common in plants.
• Types of asexual reproduction include: simple binary fission, parthenogenesis, and vegetative propagation.

Types of Asexual Reproduction

• Simple binary fission in bacteria: The bacterial DNA duplicates, and the cell divides into two.
• Parthenogenesis in plants: Eggs develop into plants without fertilization. Meiosis is not involved, and the egg is diploid.
• Vegetative propagation in plants: This process produces genetically identical offspring. Methods include fragmentation (using cuttings), and the production of specialized structures like tubers and runners.

Advantages of Vegetative Propagation

• Faster than seed propagation.
• Genetically identical offspring ensure a superior plant produces unlimited copies.
• Can produce a large number of offspring.

Cell Cycle

• The cell cycle is the regular sequence of events from one cell division to another.
• It has three phases: interphase, nuclear division (mitosis), and cell division.

Mitosis

• During mitosis, a parent cell divides to produce two genetically identical daughter cells.
• Chromosomes copy themselves before mitosis.
• Cancer cells divide by mitosis, creating copies of the parent cell.
• Uncontrolled cell division increases cancer risk.

Importance of Mitosis

• Growth of the organism
• Tissue Repair
• Asexual reproduction
• Development: increase in cellular complexity to specialize functions
• Initially, a zygote rapidly divides by mitosis many times to make a large mass of genetically identical cells.

Stages of Mitosis

• The notes describe details of prophase, metaphase, anaphase, and telophase stages in graphic form

Importance of Meiosis

• Meiosis is a reduction division.
• Involved in producing gametes (haploid cells) for sexual reproduction.
• Gametes are variable due to crossing over and independent assortment.

Stem Cells

• Undifferentiated cells that divide by mitosis.
• Types include embryonic stem cells and adult stem cells
• Embryonic stem cells can differentiate into any specialized cell type.
• Adult stem cells differentiate into specific cell types.

Sexual Reproduction in Flowering Plants

• Flowers are the reproductive organs of plants.
• Flowers can be bisexual (have both male and female organs) or unisexual (have only male or female organs).
• Structures in a typical flower include sepals, petals, stamens (with anthers and filaments), and a carpel (with stigma, style, and ovary).
• Functionally, sepals protect the bud. Petals attract pollinators. Stamens produce pollen (male gametes). Carpels produce ovules (female gametes).

Pollination

• Transfer of pollen from anther to stigma
• Types include self-pollination (within the same flower or plant) and cross-pollination (between different flowers or plants).
• Factors affecting pollination include flower structure (e.g., wind or insect pollination), time differences in gamete maturation.

Methods of Pollination

• Insects: insects attracted to flowers by color and scent, pollen sticks to their bodies and transferred to another flower.
• Wind: pollen grains are carried by the wind, have smooth, light pollen and feathery structures.

Development of Pollen Grains and Male Gametes

• Pollen grains develop from pollen mother cells through meiosis.
• Pollen walls are very resistant.
• The mature pollen grain contains two nuclei (generative and pollen tube nuclei).

Development of Ovules and Female Gametes

• Ovules develop within the ovary of the flower.
• A specialized part of the ovule called the embryo sac contains the egg cell.
• Fertilization occurs after pollen has reached a stigma.

Fertilization in Plants

• Union of pollen grain and egg cell in the ovule
• A pollen tube grows from the pollen, carrying male gametes to the egg
• Double fertilization: one sperm fuses with egg (embryo) and one sperm fuses with polar nuclei to form endosperm.

Seed Germination

• Development of the zygote to embryo.
• Breakdown of stored food reserves (starch and proteins) through enzymes to provide resources for embryo growth.
• Stages including absorption of water, radicle formation, plumule (shoot) formation, and the use of stored food reserves from cotyledons.

Dispersal of Seeds and Fruits

• Method of carrying seeds and fruits away from the parent plant to a new location (important for preventing overcrowding and disease).
• Methods include wind, water, animals.

Practical Work: Germination of Mustard Seeds

• Set up different conditions for seed germination (water, warmth, oxygen, and light).
• Monitor the germination process through observation.

Reproduction in Humans- Male Reproductive System

• Structures and functions of the testes , epididymis , vas deferens , urethra , prostate gland , and seminal vesicles
• External Genitalia include penis
• Function of each part in the reproductive process

Reproduction in Humans-Female Reproductive System

• Ovaries: are the female sex glands that produce ova (eggs) and sex hormones during ovulation phase
• Oviducts (fallopian tubes): the site of fertilization.
• Uterus (womb): the site for implantation of a fertilized egg, development of the embryo, and pregnancy.
• Cervix: the opening to the uterus
• Vagina: receives the penis during sexual intercourse, and facilitates the passage of the baby during birth
• External Genitalia include vulva (or external genitals)

Puberty

• The period of sexual maturation
• Physical changes (hair growth, voice change, breast development, and reproductive system maturation).
• Emotional and behavioral changes due to hormonal changes
• Timing and differences between sexes

Gametes

• Gametes (sperm and ova) are the reproductive cells.
• Size, Number and structure differ between sperm and ovum.

Female Sexual Cycles

• Hormonal control (FSH, LH, estrogen, and progesterone) that regulate the ovarian cycle and uterine lining.
• Phases of the cycles: menstruation, follicular phase, and luteal phase.
• Changes in the lining of the uterus (endometrium) during the cycle

Ovarian and Menstrual Cycle

• The ovarian cycle regulates the production of ova and related hormones.
• The menstrual cycle regulates the changes in the uterine lining in response to the ovarian cycle.

Fertilization and Implantation

• How sperm reaches the egg
• Sequences of events starting from fertilization leading to implantation (zigotic division into embryo)

Embryonic Membranes

• The chorion, amnion, and amniotic fluid play in protecting and nourishing the developing embryo (fetus)

Care of Mothers during Pregnancy

• Balanced diet, avoiding smoking, and no drugs except under consultation with a doctor
• Immunizations for the mother or fetus health (German measles).

Feeding a Baby

• Advantages of breast milk versus formula milk
• Factors related to the choice of how to feed babies and the problems related to these choices.

Infertility - causes, treatments

• Causes of infertility in males and females.
• Techniques used to treat infertility (fertility drugs, and in vitro fertilization)

Social Aspects of Reproduction

• Family, social and economic issues arising from decisions regarding reproduction

This quiz covers the fundamentals of cell division and the various methods of asexual reproduction in plants, including binary fission, parthenogenesis, and vegetative propagation. Understand the advantages of these reproduction methods and how they contribute to plant growth and sustainability.