Notes, summaries, assignments, exams, and exercises for Biology for Secondary education

The Circulatory System

1. The circulatory system is responsible for transporting nutrients to and from the cells in the body. It is made up of the heart, blood vessels, and the blood.

2. The function of the internal environment is to give nutrients needed to cells. It is located in the interstitial fluid.

3. Blood carries nutrients that go from the blood vessels to the interstitial fluid. Cells found in tissues exchange substances with the interstitial fluid.

4. Cells get rid of waste products with the help of the interstitial fluid that collects this.

5. Cells would not obtain nutrients.

6.1. It transports nutrients and oxygen to the cells. 2. It removes waste: CO2, urea, salts. 3. Defends the organism against infections. 4. Helps to control body...

Tissues

Types of Tissues

• Epithelial Tissue: Covers the interior and exterior body surfaces.
• Connective Tissue: The most abundant type of tissue.
• Nervous Tissue: Transmits nerve impulses.
• Muscle Tissue: Provides movement.

Homeostasis

Homeostasis is the maintenance of a constant internal environment within an organism. One mechanism to achieve homeostasis is feedback inhibition, where a stimulus produces a response that opposes the original stimulus.

Nutrition

Macronutrients

• Carbohydrates: The major source of energy in the body.
• Fats: A combination of glycerol and fatty acids. They absorb fat-soluble vitamins, store energy, and protect body organs.
• Proteins: Molecules that supply raw materials for growth and repair.

Micronutrients

• Vitamins: Organic molecules

Classification of Cell Organelles

Organelles without membrane: The cell wall, ribosomes, and cytoskeleton are non-membrane-bound cell organelles. They are present both in the prokaryotic cell and the eukaryotic cell.

Single membrane-bound organelles: Vacuole, lysosome, Golgi apparatus, and endoplasmic reticulum are single membrane-bound organelles present only in a eukaryotic cell.

Double membrane-bound organelles: Nucleus, mitochondria, and chloroplast are double membrane-bound organelles present only in a eukaryotic cell.

Let us learn more in detail about the different cell organelles in brief.

Key Cell Organelles and Their Functions

Plasma Membrane

The plasma membrane, also called the cell membrane, is the membrane found in all cells that...

Yeast

Yeast is an unicellular saprophytic fungus present in the air and on the surface of fruit. Yeast causes the spoilage of fruit, jam, honey, and is used in the production of bread, beer, and wine. It feeds on carbohydrate foods, flourishes at 25C-30C, is killed above 60C, requires moisture for growth, can live with or without oxygen, and requires time to grow. It reproduces asexually through budding, where a cell develops a bud, the nucleus moves towards the bud, the nucleus divides in two, a wall develops and divides the bud from the parent cell, and the bud separates from the cell. Yeast has granular cytoplasm, food vacuoles, vacuole, and a cell wall.

Food Preservation

Food preservation involves long term storage, preventing enzyme activity...

Evolutionary Theories

Punctuated Equilibrium vs. Neo-Darwinism vs. Neutralism

• All three theories propose evolutionary change.
• Punctuated Equilibrium: Evolutionary changes occur rapidly and abruptly.
• Neo-Darwinism: Evolutionary changes occur gradually over time.
• Neutralism: Most mutations have no effect on natural selection.

Barriers to Genetic Isolation

• Geographical
• Sexual
• Physiological
• Chromosomal
• Ethological

Ecological Concepts

Abiotic and Biotic Factors

• Abiotic Factors: Non-living factors that affect ecosystems (e.g., temperature, pH, wind)
• Biotic Factors: Living components that affect ecosystems (e.g., disease, predation, competition)

Biomass

- Total dry weight of organic matter in organisms or ecosystems. - Includes carbohydrates, proteins, etc.

Ecosystems

Food and Essential Nutrients

Food is our source of nutrients. Nutrients are biomolecules our body needs to sustain vital functions. They are the chemical components of food, the building blocks and energy sources our cells require to live.

Basic Nutritional Requirements

• Energetic: Some nutrients are broken down in mitochondria to extract energy.
• Structural: Some nutrients are building blocks of body structures.
• Regulatory: Some nutrients are necessary in small quantities to regulate body metabolism.

Carbohydrates (Glucids)

Biomolecules present in bread, cereals, potatoes, pasta, etc. They provide energy to cells, and some of them must be consumed on a regular daily basis.

Simple and Complex Glucids

Simple Glucids (Sugars)

Sweet taste, small molecules....

Key Characteristics of the Animal Kingdom

• Multicellular with differentiated tissues and organs
• Eukaryotic cells
• Heterotrophic: Feed on other living things
• Motile: Capable of active movement
• Sensitive to environmental changes
• Possess an internal or external skeleton
• Found in aquatic and terrestrial environments

Invertebrates and Vertebrates

• Invertebrates: Do not possess a spinal column (e.g., butterflies, sea urchins).
• Vertebrates: Possess a spinal column (e.g., cats, frogs).

Types of Body Symmetry

• Radial Symmetry: Body parts arranged around a central axis (e.g., starfish).
• Bilateral Symmetry: Body can be divided into two mirror-image halves (e.g., insects, vertebrates).

Animal Feeding Strategies

Dietary Classifications:

• Carnivores
• Herbivores
• Omnivores

Specific

Characteristics of Poriferans

Poriferans, also called sponges, are aquatic organisms (the majority of them are marine organisms) that either have no symmetry or have radial symmetry. Their bodies, which have a tube shape, a cup shape, or an irregular shape, have multiple pores that are interlinked by thin channels. These channels lead to a central cavity, called the atrium, which is linked to the outside by an opening called the osculum. Inside the channels, there are cells known as choanocytes, which are specialized in capturing food.

Poriferans stay upright due to a skeleton made of small spines called spicules. They feed by filtration. Water, which contains food particles, enters through the pores and exits through the osculum with the food...

The Sense of Hearing and Balance

The sense of hearing is located inside the ears. Sounds are vibrations of the air, received by the eardrum. The eardrum transfers these vibrations to the cochlea, where mechanoreceptors transform them into nerve impulses. These impulses then travel to the brain through the auditory nerve. The sense of balance is also located inside the ear and is closely related to the sense of hearing.

The Organization of the Nervous System

The nervous system is composed of two main divisions: the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

Central Nervous System (CNS)

• The Central Nervous System (CNS) comprises the brain and the spinal cord. This is where all stimuli are evaluated, and responses are generated.