IGCSE Biology Year 10/11 Midterm Semester 1 Flashcards

Comprehensive practice flashcards covering characteristics of life, respiration, classification, pathogens, cell structure, transport, biological molecules, and human nutrition.

Movement

The ability of organisms to move from place to place (locomotion in animals) or change their orientation.

Respiration

Chemical reactions in cells that release energy (ATP) from food, such as glucose.

Sensitivity

The ability to detect and respond to changes in the environment, such as light, temperature, or sound.

Control

The ability to regulate internal conditions, also known as homeostasis (e.g., controlling blood glucose or water content).

Growth

A permanent increase in the size of an organism or the number of its cells.

Reproduction

The production of offspring to pass on genetic material, which can be sexual or asexual.

Excretion

The removal of toxic waste products of metabolism, such as $CO_2$ from respiration or urea in urine.

Metabolism

All of the chemical reactions that take place in the body.

Nutrition

The process of taking in and using nutrients; animals eat food while plants photosynthesise.

Aerobic Respiration (Chemical Equation)

$$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$$

Anaerobic Respiration (Yeast)

Also known as fermentation; the word equation is glucose $\rightarrow$ ethanol + carbon dioxide + little ATP.

Anaerobic Respiration (Animals)

Occurs during vigorous exercise; the word equation is glucose $\rightarrow$ lactic acid + little ATP.

Oxygen Debt

The extra oxygen required by the body after exercise to break down toxic lactic acid.

EPOC

Stands for Excess Post-Exercise Oxygen Consumption; the process of using extra oxygen after exercise to deliver it to muscles.

Unicellular

Organisms that are made of only one cell.

Multicellular

Organisms that are made of many cells.

Eukaryotic cells

Cells that contain a nucleus and membrane-bound organelles.

Prokaryotic cell

Cells that lack a nucleus or membrane-bound organelles, such as bacteria.

Autotrophs

Also known as producers; organisms that make their own food (e.g., via photosynthesis).

Heterotrophs

Also known as consumers; organisms that must eat other organisms because they cannot make their own food.

Hyphae

Thread-like structures that make up multicellular fungi and contain many nuclei.

Mycelium

A network of hyphae that forms the main body of a fungus, spreading through soil or growth material.

Saprotrophic Nutrition

A type of heterotrophic nutrition where organisms release digestive enzymes onto dead material outside their body and absorb the broken-down nutrients.

Protoctist Kingdom

Known as the "dustbin kingdom" because it includes a variety of organisms that do not fit into the animal, plant, or fungi kingdoms.

Lactobacillus sp.

A rod-shaped bacterium used to make yoghurt from milk.

Pathogen

An organism, such as a virus, bacterium, protoctist, or fungus, that causes disease in another organism.

Mycobacterium tuberculosis

The pathogenic bacterium that causes tuberculosis (TB), which affects the lungs and causes chronic cough.

Plasmodium falciparum

A pathogenic protoctist spread by mosquitoes that causes severe malaria.

Viruses

Acellular, parasitic particles that contain a protein coat and either DNA or RNA; they are not considered living because they lack the 8 characteristics of life.

Cell Differentiation

The process by which cells change their structure and organelles to become specialised for specific functions.

Pluripotent

Undifferentiated stem cells, like embryonic stem cells, that can become any type of cell in the body.

Multipotent

Adult stem cells that can only become a limited number of cell types related to the tissue they originate from.

Diffusion

The movement of solute particles from a high concentration to a low concentration down a concentration gradient.

Osmosis

The movement of water from a high water potential to a low water potential through a selectively permeable membrane.

Active Transport

The movement of solutes from a low concentration to a high concentration against a concentration gradient, requiring carrier proteins and energy (ATP).

Hypotonic solution

A solution with more water and less solute than inside the cell, causing water to move into the cell.

Hypertonic solution

A solution with less water and more solute than inside the cell, causing water to move out of the cell.

Turgor pressure

The pressure exerted by the cell membrane against the cell wall in plant cells when the vacuole is full of water.

Monomer

A small, simple molecule that acts like a building block, such as glucose or amino acids.

Polymer

A large molecule made by linking many monomers together, such as glycogen, starch, or proteins.

Triglyceride

The form of most lipids in the body, made of 1 glycerol and 3 fatty acids.

Enzymes

Biological catalysts made by living cells that speed up chemical reactions.

Active Site

The part of an enzyme where the substrate molecule binds, matching like a lock and key.

Denaturation

An irreversible change in the shape of an enzyme's active site caused by high temperatures or extreme pH, preventing it from binding to the substrate.

Benedict's Solution

A chemical used to test for glucose; a positive result turns from blue to green, yellow, orange, or brick red depending on the concentration.

Photosynthesis (Word Equation)

Carbon dioxide + water $\xrightarrow{\text{light}}$ glucose + oxygen

Chlorophyll

A green pigment in chloroplasts that captures light energy for photosynthesis.

Limiting Factor

An environmental condition, such as light intensity, $CO_2$ concentration, or temperature, that is in short supply and slows down photosynthesis.

Alimentary canal

The continuous tube of the digestive system through which food passes, from the mouth to the anus.

Ingestion

The process of taking food into the body through the mouth.

Absorption

The movement of digested food molecules from the small intestine into the blood.

Assimilation

The process where absorbed nutrients are used by cells for energy, growth, or repair.

Egestion

The removal of undigested food and waste products as faeces through the anus.

Peristalsis

The rhythmic squeezing of circular and longitudinal muscles that pushes food through the digestive system.

Bile

An alkaline substance produced in the liver and stored in the gallbladder that neutralises stomach acid and emulsifies fats into smaller droplets.

Villi

Tiny finger-like extensions in the ileum that increase the surface area for the absorption of nutrients.