Aadya Isai

1. Open Circulatory System:

In this system, the heart pumps fluid into an open space that surrounds the organs. 

• How it works: Instead of staying in veins, the fluid (called hemolymph) leaves the vessels and "bathes" the organs directly. Imagine pouring water over a sponge—the organs just soak up what they need. 

• Pressure: The pressure is very low. Because the fluid isn't confined to pipes, it moves slowly. 

• Examples: Insects (like grasshoppers), spiders, and most mollusks (like snails). 

2. Closed Circulatory System:

1. Single Circulation (The Simple Loop):

Imagine a delivery truck that only stops at the warehouse once.

• The Route: Heart to gills then to the capillary system and back to the heart.

• The Problem: When the truck goes through the gills to pick up oxygen, it has to slow down. By the time it leaves the gills to go to the rest of the body, it is moving very slowly (low pressure).

• Who has it? Fish.

2. Double Circulation (The Power Loop):

The transition from a two-kingdom system to a five-kingdom scheme represents a major shift in how we understand the complexity of life. By moving beyond just "Plants" and "Animals," biologists can more accurately categorize organisms based on their cellular structure and how they obtain nutrients.

The Five Kingdoms Explained:

1. Animal (Animalia):

Animals are multicellular organisms that do not have cell walls or chloroplasts. They are heterotrophic, meaning they must ingest other organisms to obtain energy. This kingdom includes everything from insects to mammals.

2. Plant (Plantae):

Plants are multicellular organisms with cell walls made of cellulose. They contain chloroplasts and are autotrophic, meaning they produce their own food through photosynthesis.

Comparison Table of Vertebrate Classes:

Deep Dive into the Groups:

1. Amphibians: The "Double Life":

Amphibians like frogs and salamanders are the "bridge" between water and land.

The phylum Arthropoda is so massive that scientists often group them into four major living subphyla (sometimes referred to as classes in general conversation). Each group is defined by its body segments, number of legs, and types of appendages.

1. Hexapoda (Insects):

The most successful group of animals on Earth. The name "Hexapoda" literally means "six legs."

• Key Traits: 3 body segments (head, thorax, abdomen), 6 legs, and usually 1–2 pairs of wings.

• Examples: Ants, beetles, butterflies, bees, and grasshoppers.

• Unique Fact: They are the only arthropods that have evolved the ability to fly.

In biology, organisms are categorized based on how many cells they have: unicellular (single-celled) or multicellular (many-celled). While both types of life use the same "Big Three" components—DNA, cytoplasm, and a cell membrane—they organize them in very different ways. 

1. Unicellular Organisms (The Soloists):

These organisms are composed of only one cell. This single cell must perform every job required for life: eating, moving, breathing, and reproducing. 

• Size: Mostly microscopic (invisible to the naked eye). 

• Body Plan: Very simple. If that one cell is damaged, the entire organism dies. 

• Reproduction: Usually asexual (cloning itself), which is very fast. 

The Hierarchy of Classification:

Animals are organized into large groups called phyla. Within these phyla, organisms are further divided into classes.

• Arthropods: Includes classes such as Crustacea, Insects, Arachnids, and Myriapods.

• Vertebrates: Includes classes such as Fish, Amphibia, Reptiles, Birds, and Mammals.

• Note: Mammals are further divided into subgroups like Primates, Rodents, Carnivores, and Insectivores.

The term invertebrate is commonly used to describe any animal lacking a vertebral column (backbone), though it is a label of convenience rather than a formal biological group.

This information is about Taxonomy, the science of naming and grouping living things.

Scientists use specific "checklists" to decide where an organism belongs. Here is the breakdown of the categories you provided:

The Universal Checklist:

Before looking at specific groups, scientists look for these three features that almost all living things have:

• Cell Membrane: A boundary that controls what goes in and out.

• Cytoplasm: The jelly-like fluid where life processes happen.

A miscarriage, medically known as a spontaneous abortion, is the unexpected loss of a pregnancy before the 20th week. It is a very common occurrence, affecting roughly 10% to 20% of known pregnancies, though the actual number may be higher as many happen before a person even realizes they are pregnant. 

It is important to know that in the vast majority of cases, a miscarriage is not caused by anything the pregnant person did or did not do (such as exercise, working). 

Common Causes:

The cause of a miscarriage often depends on when it occurs during the pregnancy. 

1. Chromosomal Abnormalities (Most Common):

About 50% of all miscarriages in the first trimester happen because the embryo has the "wrong" number of chromosomes. 

"Siamese twins" is a historical term for conjoined twins—identical twins who are born physically connected to each other. While the term is still used colloquially, the medical community and many modern style guides prefer "conjoined twins" as it is more accurate and avoids tying a medical condition to a specific nationality.

1. The Origin of the Term:

The name comes from Chang and Eng Bunker (1811–1874), a famous pair of conjoined brothers born in Siam (now Thailand).

• Life and Fame: They were joined at the sternum by a small band of cartilage. They were brought to the U.S. and exhibited as "The Siamese Twins," eventually becoming a world-famous sensation.

• Legacy: They eventually settled in North Carolina, married sisters, and fathered 21 children between them. They lived to be 62 years old, which remains one of the longest lifespans for unseparated conjoined twins.

CRISPR (pronounced "crisper") is one of the most significant breakthroughs in the history of science. It is a revolutionary tool that allows scientists to "edit" the DNA of living organisms—including humans, plants, and animals—with the precision of a word processor.  

It stands for Clustered Regularly Interspaced Short Palindromic Repeats.  

How It Works: 

"Molecular Scissors" CRISPR was originally discovered as a natural defense mechanism in bacteria. When a virus attacks a bacterium, the bacterium "remembers" it by storing a snippet of the virus's DNA in its own genome. If the virus returns, the bacterium uses a specialized enzyme called Cas9 to recognize and cut the intruder's DNA, neutralizing it.  

In 2012, scientists (most famously Jennifer Doudna and Emmanuelle Charpentier) figured out how to "program" this system. Now, instead of hunting viruses, we can give CRISPR a "guide RNA" that tells it exactly where to go in any DNA sequence. It then:  

A dichotomous key is a scientific tool used to identify unknown organisms (like plants, animals, or rocks) based on their visible traits. 

The word "dichotomous" comes from Greek roots meaning "divided into two parts." This is the secret to how it works: at every step, the key presents you with exactly two contrasting choices. By choosing the one that matches your specimen, you are led to the next pair of choices until the organism is eventually named. 

How it Works (The Step-by-Step):

Imagine you find a mysterious leaf in a forest. You would open your dichotomous key and start at the very first set of clues:

1. Step 1: * (a) Is the leaf edge smooth?……..Go to Step 2

• (b) Is the leaf edge jagged?………Go to Step 3

Taxonomic Hierarchy is also frequently referred to as Linnaean Taxonomy, named after Carolus Linnaeus, the Swedish botanist who created the foundation for this system in the 1700s.

Key Terms to Know:

• Taxonomic Hierarchy:

It is also frequently referred to as Linnaean Taxonomy, named after Carolus Linnaeus, the Swedish botanist who created the foundation for this system in the 1700s.

• Taxonomy: The science of naming, describing, and classifying organisms.

• Taxon (plural: Taxa): A single level or "unit" within the hierarchy. For example, "Mammalia" is a taxon at the Class level.

Definition:

Natural selection is the process by which living organisms adapt and change over time. It is one of the fundamental mechanisms of evolution, famously proposed by Charles Darwin in 1859. 

At its core, natural selection is simple: individuals with traits that are better suited to their environment are more likely to survive and reproduce. Because they survive longer, they pass those helpful traits on to their offspring, making those characteristics more common in the population over many generations. 

Examples:

1. Random Variation: Long ago, giraffe ancestors had short necks, but some were born with slightly longer necks due to random genetic differences.

2. Environmental Pressure: Food on the ground became scarce. The best leaves were high up in the trees.

Definition:

Mitosis (often misspelled as metosis) is the process where a single cell divides into two genetically identical "daughter cells."

Think of it as the body’s way of making perfect photocopies of its cells. It is how you grew from a single cell into an adult and how your body heals itself today.

Why is Mitosis Important?

• Growth: It allows organisms to grow by increasing the number of cells.

• Repair: It replaces damaged or worn-out cells (like when a cut on your skin heals).

1. Definition:

   • Selective breeding (also known as artificial selection) is the process by which humans choose specific animals or plants to breed together to develop particular phenotypic traits.

   Unlike natural selection, where "survival of the fittest" determines which traits are passed on, selective breeding is driven by human preference for utility, aesthetics, or efficiency.

1. The Core Method: Step-by-Step:

To change a population, breeders follow a simple, repeating cycle:

1. Selection: Identify a desirable trait (e.g., faster growth, higher milk yield, or a calm temperament).

Stages of Meiosis:

Meiosis is a special type of cell division that makes sex cells (sperm and egg).

It reduces the chromosome number from diploid (2n) (two sets) to haploid (n) (one set) and creates variation.

Meiosis I – Reduction Division:

This stage reduces the chromosome number by half.

1. Prophase I

1. Genes:

   • Genes are passed down through sexual reproduction with gametes.

a) eggs (female gamete) - the female gamete inherits the MTDNA (mitochondrial DNA) from the mother. This one of the very few things you inherit from one specific parent. The MTDNA can only be passed down by women, creating a maternal line.

b) sperm (male gamete) - the male gamete decides your sex (gender). XY meaning a male and XX meaning female.

2. DNA:

   • The gametes hold traits within the nucleus, in the form of DNA.

   
   

Inheritance:

Inheritance is the biological process by which characteristics are passed from parents to their offspring through genes. It explains why offspring show similarities to their parents while also having some differences.

Genes and Chromosomes:

Genes are small units of heredity made of DNA.

They are located on structures called chromosomes, which are found in the nucleus of cells.

Each gene carries specific instructions that control traits such as eye colour, height, skin tone, and blood group.

Environmental problems are mainly caused by human activities that disturb the natural balance. They affect air, water, land, and living organisms across the planet. If not controlled, these problems can cause long-term damage to the Earth.

• Major Problems:

These include pollution, climate change, ozone layer depletion, loss of biodiversity, and ocean acidification. Each of these problems is linked and together they threaten ecosystems and human life. Solving one problem often helps reduce the impact of the others.

• Causes:

Industrialisation, burning of fossil fuels, deforestation, urbanisation, and overuse of natural resources increase environmental damage. Poor waste management and excessive consumption further worsen these problems. Population growth also increases pressure on natural resources.

• Effects:

Preserving wetlands:

In 1971 representives from 21 nations met in Iran to discuss the threat to the worlds wetlands. They all signed an agreement called the Ramsar Convention. This listed things that they would all try to do to save the Earth’s wetlands.

Improvement:

By 2025 there has been progress in global wetland conservation since the Ramsar Convention was first signed in 1971 — including a stronger strategic framework, more internationally recognized wetland sites, and increased engagement at national and city levels. However, wetland loss and degradation continue, meaning the Convention’s work is still very much needed and evolving.

Protecting the ozone layer:

1. Introduction about habitats:

   a) Definition:- A habitat is the natural home or environment where plants, animals, and other organisms live.

   
   

   b) Types of habitat:- forests, rainforests, deserts, polar and water.

   
   

2. Habitat destruction:

   Habitat destruction is when natural environment are changes so severely, mainly by human activities, that they can no longer support their native species, leading to displacement or death, reduces biodiversity and potential extinction.
   

3. Types of deforestation:

   
   

1. Definition:- A rapid growth of microscopic algae in water, often resulting in à coloured scum on the surface.

   An algal bloom is a rapid, excessive growth of algae in fresh water or marine environments, often turning the water discoloured (green, red, brown) due to high nutrient levels, especially nitrogen and phosphorus from fertiliser runoff or wastewater.

   
   

   These blooms can be harmless but are often harmful, causing oxygen depletion (hypoxia) that kills fish and other aquatic life.

1) Introduction:

A) Definition:- Pollution is the introduction of harmful substances or energy (like - heat, sound, light) into the natural environment, causing adverse effects on living organisms and ecosystems, making the surrounding impure and unsafe.

B) Causes:- Pollution stems rein hunan activities like burning fossil fuels for energy and transport; industrial emission, vehicle exhaust, agricultural chemicals (pesticides/fertilisers), and improper waste disposal (sewage, plastic, garbage burning).

2) Causes of water pollution:

A. Factories:- Factories cause water pollution by discharging untreated waste water filled with toxic chemicals, heavy metals (like-led, mercury) dyes, oils, and pathogens into rivers, lakes, and groundwater.

B. House hold works:- House holds pollutes water through untreated sewage release, poor drainage systems, and ground water sewage.

Animal population size is shaped by growth factors (like - birth and immigration) and population decline (like - deaths and emigration), all controlled by limiting factors like food supply, water, shelter, predation, diseases, space, as well as environmental conditions (climate, light) and biological interactions (competition, symbiosis) ultimately determining the habitat’s carrying capacity.

How food supply impacts growth: A) Food supply:

Food supply is a primary driver of animal population size; abundant food allows for more births and better survival, leading to population growth, while scarcity cause declines through starvation, reduced reproduction, and increased stress/predation.

B) Predators:

• Predation significantly effects animal population by creating dynamic cycles; more prey leads to move predators, which then reduces the prey to rebound, and restarting the cycle.

1. Definition:

   • Population is the total number of individuals of the same species living in a specific area at a particular time.

   
   

2. Why is population important?

   Population is important because it determines how living organisms survive, interact, and use resources in an area.

   
   

   • Population size helps us understand how many individuals of a species are living in a place and whether their numbers are increasing or decreasing.

   
   

   • It affects the availability of food, water, space, and shelter, since resources are limited.

   
   

1. Which is better? Increase or decrease in population?

   
   

   • Population changes are not automatically better or worse

     • Neither a population increase nor a decrease is inherently “better.”

     • The key factor is whether the population size is balanced with available resources and opportunities.

     
     

   • Benefits of population increase

     • An increase can be positive if there are sufficient jobs, food, housing, education, and healthcare.

     
     

1. Definition: Decomposers are organisms that break down dead organisms and release the nutrients from the dead matter into the environment around them. In simpler words - Decomposers are living things that break down dead plants and animals and return their nutrients to the environment.
   

2. The main types of Decomposers: • Bacteria - tiny organisms that break down dead plants and animals into simpler substances. • Fungi - such as mushrooms and molds, which absorbs nutrients from dead matter. • Detritivores - animals like earthworms, termites, and beetles that eat dead materials and they help to break it into smaller pieces.
   

3. Natural VS Artificial Decomposers: • Natural decomposers are living organisms that break down dead plants, animals, and organic waste into simpler substances. By doing this, they return nutrients to the soil and keep the environment clean. Examples: bacteria and fungi (main decomposers), earthworms and insects (help by breaking waste into smaller pieces). • Artificial methods of decomposition are…

1. The process:

   • The process of decomposing is how nature recycles dead and waste matter back into the ecosystem, allowing materials from once-living organisms to be reused.

     
     

   • Decomposers such as bacteria and fungi act on dead plants, dead animals, and organic waste, beginning the breakdown of this material.

     
     

   • First, they release enzymes onto the dead material, which start the chemical breakdown from the outside.

     
     

   • These enzymes break complex organic substances like proteins, fats, and carbohydrates into much simpler molecules.

     
     

   • Next, decomposers absorb these simpler substances for their own energy and growth, helping them survive and reproduce.

     
     
   
   

1. Dead matter:

   • Dead matter refers to organic material from once-living organisms (plants, animals, waste) that is no longer alive and is in the process of breaking down

   
   

   • Simpler words - Dead matter is anything that was once alive—like plants, animals, or waste—that has stopped living and is now slowly being broken down and recycled by nature.

   
   

2. Organic matter:

   • Organic matter (OM) refers to carbon-based compounds from decomposed plants, animals, and microorganisms.

   
   

   • Simpler words - Organic matter is made of carbon-based materials that come from plants, animals, and microorganisms after they die and start to break down.

   
   

Definition

Dopamine is a chemical messenger in the brain known as a neurotransmitter. It helps nerve cells communicate with each other and plays a major role in movement, motivation, pleasure, and learning.

Introduction

Dopamine is essential for normal brain and body function. It influences how we feel pleasure, how motivated we are to act, how we move our muscles, and how we pay attention and learn. Balanced dopamine levels are necessary for both mental and physical health.

Production and Release

Dopamine is produced in specific areas of the brain, mainly the substantia nigra and the ventral tegmental area. Once produced, it is released into the space between nerve cells, where it carries messages by binding to dopamine receptors on nearby neurons.

1. What does“tangled” means?

A tangled cord usually refers to a nuchal cord (wrapped around the baby’s neck) or the cord looping around the baby’s body, arm, or leg. This happens because babies move a lot in the amniotic fluid, and the cord can naturally wrap or twist.

2. Is a tangled cord dangerous?

Most of the time, no.

The umbilical cord is designed to be very strong and flexible, and Wharton’s jelly protects the blood vessels from being squeezed. That means:

• Blood usually continues flowing normally.

Introduction:

During pregnancy, the fetus cannot breathe, eat, or remove waste on its own. Instead, it depends entirely on the placenta. The organ that physically links the fetus to the placenta is the umbilical cord. It forms early in development (around week 5) and grows throughout pregnancy, usually reaching 50–60 cm in length by birth. Because of its protected structure, the cord can bend, twist, and stretch without cutting off blood flow.

Definition:

The umbilical cord is a flexible, tube-like structure that connects a developing fetus to the placenta. It contains blood vessels that transport oxygen, nutrients, and waste between the fetus and the placenta, acting as the fetus’s lifeline during pregnancy.

Structure:

1. Introduction:

   • Definition - Coma is a deep state of unconsciousness in which a person cannot wake up, cannot respond to sound, touch, or pain, and shows very limited brain activity because the brain is not functioning normally.

   • Consciousness VS unconsciousness:

   Consciousness - means a person is awake, aware of themselves, and able to respond to what is happening around them.

   
   

   Unconsciousness - means a person is not aware, cannot respond, and does not have control over their actions or surroundings.

   So, coma is a deep form of unconsciousness where the brain is not working normally and the person cannot be woken up.

   
   

1. Introduction:

   
   

   1. Definition:

   • Food web - A food web is a network of many connected food chains that shows how energy and nutrients move between organisms in an ecosystem.

   
   

   • Energy flow - Energy flow is the movement energy from that sun to producers and then through different organisms as they eat and are eaten.
   

2. Why are they needed?

   
   

   Food web:

   
   

1. Introduction

Tourette syndrome is a neurological condition where a person has tics — movements or sounds they cannot fully control.

Keywords: tics, neurological, childhood

2. Types of Tics

a) Motor Tics

Movements of the body.

1. Introduction of ecology:

   • Ecology is the study of how living things interact with eachother and with their environment.

   
   

   • It looks at how plants, animals, and other organisms depend on air, water, soil and other living things to survive.

   
   

   • A scientist who learns the study of ecology is called an ecologists

2. Ecosystem

   • Definition - An ecosystem is a system where living and non-living things interact.

   
   

Definition - OCD (Obsessive–Compulsive Disorder) is a mental condition where a person gets unwanted, repetitive thoughts (obsessions) and feels the need to do certain actions again and again (compulsions) to reduce anxiety or discomfort, even if they know the actions don’t actually help.

Cause: 1. Brain chemistry

• Imbalance in certain brain chemicals (like serotonin) can affect how the brain controls fear, worry, and habits.

2. Brain structure

• Some areas of the brain that handle decision-making, checking, and danger signals may work differently or be overactive.

Definition - Adaptation is the process by which animals develop physical or behavioral traits that improve their ability to survive and reproduce in their specific environment.

Why? 1. To get food

If the environment changes or food becomes harder to find, animals with features that help them get food survive better.

Example: A giraffe’s long neck helps it reach leaves high up.

2. To stay safe from predators

Animals develop features that help them hide, run, or defend themselves.

1. Definition - Adaption in plants is the process of developing special features that allow them to survive and thrive on a particular environment or habitat.

2. Why? - Plants need to adapt so they can survive on the place they live. Every environment has challenges, and adaptation help plants handle those challenges.

3. How? - plants adopt in these ways:

   • By changing their structures (structural adaptation)

   • By changing how they look inside (physiological adaptation)

   • By changing how they behave (behavioural adaptation)

   
   

Treatment

There is no cure, but treatment slows symptoms and improves quality of life.

Medicines

• Cholinesterase inhibitors (donepezil, rivastigmine, galantamine)– Help with memory, thinking, and behaviour in early to moderate stages.

• Memantine– Helps in moderate to severe stages by improving daily function and reducing confusion.

• Newer drugs aim to reduce amyloid protein buildup, but they work only for some patients.

1. Definition - Alzheimer’s disease is a long-term brain disorder that slowly damages memory, thinking, and behaviour.

   
   

2. Changes in a person’s life with Alzheimer’s

   • They forget recent events and repeat things.

   • Daily tasks like cooking or dressing become harder.

   • They get confused about time, places, and people.

   • Mood and behaviour change (easily upset, worried, or angry).

Cell Cycle — How Cells Prepare to Divide

The cell cycle is the full series of steps a cell goes through before dividing.

Key phases:

1. Interphase

   • This is where the cell spends most of its life.

   • It has three sub-phases:

     
     

What Is Cell Division?

• Cell division is the process by which a parent cell splits into two (or more) daughter cells.

• In eukaryotes (cells with a nucleus), this usually happens as part of the cell cycle: a cycle of growth, DNA replication, and division.

• There are two main types of cell division in eukaryotes: mitosis and meiosis.

Why Cell Division Is Important

• Growth: your body need more cells to grow.

Fruit (definition):In botany, a fruit is the mature, ripened ovary of a flowering plant, usually containing seeds. It forms after fertilization and helps protect and disperse the seeds.

Simple explanation:

A fruit is the part of a plant that develops from the flower and holds the seeds. Examples: apples, oranges, tomatoes, and berries.

Key points:

• Comes from the flower of the plant

• Contains seeds (botanical definition)

Parasitic plants:

These are plants that cannot make all their own food, so they attach to another plant and take water, nutrients, or sometimes even sugars from it. The plant they take from is called the host.

How they work:

They use a special structure called a haustorium to connect to the host’s tissues and absorb what they need.

Types:

ADHD stands for Attention Deficit Hyperactivity Disorder. It’s a neurodevelopmental condition that affects how a person focuses, controls impulses, and manages energy. People with ADHD may experience:

• Inattention: Trouble focusing, getting easily distracted, forgetting things, or having difficulty organizing tasks.

• Hyperactivity: Feeling restless, needing to move constantly, or talking excessively.

• Impulsivity: Acting without thinking, interrupting others, or struggling to wait for their turn.

ADHD isn’t caused by laziness—it’s linked to differences in brain development and function, particularly in areas that manage attention and self-control. It can show up in children and continue into adulthood, though the symptoms may change over time.

ADHD Overview

Fertilisation in plants occurs when the sperm cell from the pollen fuses with the egg cell in the ovule.

Here’s what happens:

• After pollen lands on the stigma, it forms a pollen tube that extends down through the style.

• The male cell inside the pollen travels through this tube.

• In the ovary, the tube reaches an ovule.

• The male cell then fuses with the egg cell inside the ovule.

Gangrene is a dangerous condition where part of the body’s tissue dies because it either loses its blood supply or becomes severely infected. When blood flow is blocked, the tissue cannot get oxygen or nutrients, so it slowly breaks down and dies. This causes dry gangrene, where the skin becomes dark, dry, and shriveled. When bacteria enter a wound and spread quickly, it leads to wet or gas gangrene, which damages tissue much faster and can produce swelling, fluid, and sometimes gas inside the skin.

It becomes life-threatening because the infection does not stay in one place. As bacteria spread deeper, they can reach the muscles and even the bone, causing a serious bone infection called osteomyelitis. If the bacteria enter the bloodstream, they can cause sepsis, where blood pressure drops, organs start failing, and the body can no longer fight the infection. The toxins released by the bacteria also…

Transpiration Pull

• Happens in the whole plant, mainly from leaves upward.

• When water evaporates from tiny pores (stomata) in the leaves, it creates a pulling force.

• This pull drags the entire column of water upward from the roots to the leaves.

• Works through xylem tubes.

• It’s like water forming a long straw, and the evaporation at the top pulls everything up.

Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds. Pollinating agents can be animals such as insects, for example bees, beetles or butterflies; birds, and bats; water; wind; and even plants themselves. Pollinating animals travel from plant to plant carrying pollen on their bodies in a vital interaction that allows the transfer of genetic material critical to the reproductive system of most flowering plants.

• Some flowers are specially shaped or coloured to make pollination easier.

• After successful pollination, the flower usually begins changes that lead to fertilisation, which later forms seeds and sometimes fruits.

• Not all plants need the same method; some

depend on their flower structure, timing, or

scent to improve pollination.