Key Concepts in Biology: Life Processes and Cell Structure

8 life processes

Nutrition, respiration, excretion, sensitivity (response to surroundings), movement, control of internal conditions, reproduction, growth and development.

Structures in both animal and plant cells

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes.

Unique structures to plant cells

Cell wall, chloroplasts, and large central vacuole.

Function of nucleus

Contains genetic material and controls cell activities.

Function of mitochondria

Site of aerobic respiration, produces energy (ATP).

Role of enzymes

Biological catalysts that speed up metabolic reactions.

Effect of temperature on enzymes

Increases activity to an optimum point, then denatures enzyme at high temperatures.

Active site

The region of the enzyme where substrate binds.

Effect of extreme pH on enzyme activity

Enzyme denatures, altering the shape of the active site.

Purpose of respiration

To release energy in the form of ATP for cellular processes.

Word equation for aerobic respiration

Glucose + oxygen → carbon dioxide + water (+ energy)

Word equation for anaerobic respiration in animals

Glucose → lactic acid (+ energy)

Diffusion

Movement of particles from a high to a low concentration.

Osmosis

Diffusion of water through a partially permeable membrane.

Active transport

Movement of substances against the concentration gradient using energy.

Levels of biological organisation

Organelle → cell → tissue → organ → system → organism.

Cell differentiation

The process by which a cell becomes specialized for a specific function.

Advantage of stem cells in medicine

Can differentiate into any cell type to repair damaged tissues.

Common features of plants

Multicellular, photosynthetic, cellulose cell walls, store starch/sucrose.

Features of animals

Multicellular, no chloroplasts, nervous coordination, store glycogen.

Features of fungi

Saprotrophic nutrition, chitin cell walls, some single-celled (e.g. yeast).

Features of protoctists

Microscopic, some like animals (e.g. Amoeba), some like plants (e.g. Chlorella).

Features of bacteria (prokaryotes)

No nucleus, circular DNA, cell wall, may photosynthesise or feed off others.

Pathogen

A microorganism that causes disease.

Example of a virus

HIV (causes AIDS), Influenza virus (causes flu), Tobacco mosaic virus.

Structures of the thorax involved in breathing

Ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli, pleural membranes.

Role of diaphragm and intercostal muscles

Contract/relax to change thoracic pressure and enable ventilation.

Adaptations of alveoli for gas exchange

Large surface area, thin walls, moist lining, good blood supply.

Effects of smoking

Damages alveoli, reduces gas exchange, increases risk of coronary heart disease.

Elements in carbohydrates, proteins, and lipids

C, H, O in all; proteins also contain N; lipids contain glycerol and fatty acids.

Structure of starch/glycogen

Made from simple sugars (glucose).

Importance of a balanced diet

Provides all essential nutrients: carbs, proteins, fats, vitamins, minerals, fibre, water.

Vitamin that prevents rickets

Vitamin D.

Energy requirement varies with

Age, activity level, pregnancy.

Parts of the human alimentary canal

Mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine (colon and rectum), anus.

Peristalsis

Wave-like muscle contractions that move food through the digestive tract.

Role of amylase and maltase

Amylase breaks starch → maltose; maltase breaks maltose → glucose.

Bile

Made in liver, stored in gall bladder; neutralises stomach acid and emulsifies lipids.

Function of villi in small intestine

Increase surface area for absorption; contain capillaries and lacteals.