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

Su,Aalo Iyo Jawabo biology 

• 1. a) i) Define transport

• Movement of substances from one part of the body to another

  ii) Explain the necessity of transport in plants and animals

• make nutrients move from one point to another

• movement of respiratory gases i.e. oxygen and carbon IV oxide

• elimination of metabolic wastes

• movement of hormones

• movement of water

• movement of salts

• movement of enzymes

  b) i) Describe the structure and function of root hair

• root hairs are found near the root tip

• they are cells with elongated finger-like projections which are in contact with soil particles

• they are permeable to water and mineral salts hence are used to absorb Water and mineral salts

• There large number offers a large surface area for absorption of water and mineral salts.

The Nephron

The nephron is the functional unit of the kidneys, responsible for filtering blood and producing urine. Each kidney contains over one million nephrons.

Parts of the Nephron

• Bowman's Capsule: Surrounds a tiny network of capillaries.
• Tubule: Shaped like a handle, the tubule of several nephrons empties into a larger tube called a collecting duct.
• Collecting Ducts: Move urine into the renal pelvis.

Kidney Function

1. Filtration: Molecules exit the bloodstream and enter the Bowman's capsule, forming filtrate.
2. Reabsorption: As filtrate travels through the tubule, some molecules are reabsorbed by the capillaries. Glucose, 99% of water, a small amount of urea, and salts return to the blood.
3. Excretion: The remaining filtrate forms urine, which is excreted

Abiogenesis

Process through which life appeared from non-living matter, such as simple organic molecules.

Cyanobacteria

Photosynthetic organisms responsible for the existence of oxygen in the atmosphere.

Homologous Organs

Organs that share an evolutionary origin and structure, but may have different functions. They evidence divergent evolution. Examples: whale and bat extremities.

Analogous Organs

Organs with the same function but different evolutionary origins. They evidence convergent evolution. Examples: insect and bird wings.

Vestigial Organs

Organs that are disappearing because they are no longer useful. Examples: kiwi and cassowary wings.

Evolutionary Lineage

Fossils show progressive transformations, providing evidence of evolution and allowing...

Cellular Transport and Water Potential

Diffusion

The movement of molecules from an area of high concentration to an area of low concentration through a partially permeable membrane. (Osmosis is the same but with water molecules)

Concentration Gradient

The difference in concentration of a substance between two different areas.

Active Transport

The uptake of particles by cells against a concentration gradient. It requires energy and a carrier protein.

Partially Permeable Membrane

A membrane that allows small molecules of water and certain solutes but does not allow the passage of large solute molecules.

Kinetic Energy

The energy of movement

Brownian Motion

The random movement of particles

Water Potential

The ability for a substance or cell to accept more water....

Levels of Organization

From Atoms to Organisms

Atom, molecule, organelle, cell, tissue, organ, organ system

Inorganic Biomolecules

• Water
• Mineral salts

Organic Molecules

• Carbohydrates
  • Monosaccharides: one molecule; examples: glucose, fructose
  • Disaccharides: two monosaccharides; examples: sucrose, maltose
  • Polysaccharides: many monosaccharides; examples: glycogen, cellulose
• Proteins: macromolecules composed of small molecules called amino acids; examples: collagen, hemoglobin, antibodies
• Lipids: examples: fats, phospholipids, cholesterol. Fats break down into fatty acids and glycerol.
• Nucleic acids: macromolecules composed of nucleotides, two types: DNA and RNA; examples: genes

Cells

Simplest living unit. Living things can be unicellular organisms or multicellular...

Fat vs. CHO

CHO is both aerobic and anaerobic, BUT it has limited stores. It does, however, have a greater energy yield per unit of O2 (fat is about 10% less).

Sparing CHO

Sparing CHO by upregulating lipid oxidation should be advantageous. This leads to:

• More lipid oxidation
• Decreased sympathetic nervous system activity (recruitment of CHO)
• Increased mitochondrial volume and enzymatic adaptations
• Reduction in signals that activate major CHO metabolic enzymes

In lower exercise intensity, more FFA and TG are present in plasma. The more intense the exercise becomes, the more glycogen/glucose is used. At ~62% of VO2 max, the highest lipid oxidative rate is experienced.

Nutritional Strategies to Improve Lipid Oxidation

• High-fat diets: long term vs. short

Transcription and mRNA Processing

Transcription occurs within the nucleus. During this process, introns are removed from the pre-mRNA, creating a mature mRNA molecule. This mature mRNA then migrates from the nucleus to the cytoplasm.

Translation Initiation and Elongation

Once in the cytoplasm, the mRNA is recognized by the ribosome. This recognition occurs via specific sequences in bacteria and the 5' cap in eukaryotes. The ribosome then initiates the translation process.

tRNA molecules act as adapters between amino acids and mRNA. Each tRNA has a region that binds to a specific amino acid and another region, the anticodon, that recognizes a triplet of nucleotides (a codon) in the mRNA.

Translation begins when the ribosome identifies the start...

Circulatory System

Deoxygenated blood from the body returns to the right atrium of the heart through the superior and inferior vena cavae. The right atrium contracts, pushing the blood through the tricuspid valve into the right ventricle. The right ventricle contracts, pumping the deoxygenated blood through the pulmonary valve into the pulmonary artery. The pulmonary artery carries the deoxygenated blood to the lungs, where it picks up oxygen and releases carbon dioxide through the process of gas exchange. Oxygenated blood returns from the lungs to the left atrium of the heart via the pulmonary veins. The left atrium contracts, pushing the oxygenated blood through the mitral valve into the left ventricle. The left ventricle contracts, pumping...

The heart: double circulatory system

Vena cava - body to the heart (DO), pulmonary artery heart to lungs (DO), pulmonary vein - lungs to heart (O), aorta - heart to body (O). Arteries take blood away from the heart, veins take it towards the heart, Pulmonary means lungs. Valves make sure blood flows in a one way direction. Blood goes from heart to lungs to be oxygenated via the pulmonary artery. The now oxygenated blood goes back to the heart via the pulmonary vein to be pumped around the body via the aorta. Once the blood has been round the body, it is pumped to the heart via the vena cava to be sent to the lungs again for oxygenation then the cycle repeats.

Coronary heart disease

The coronary artery supplies blood to the heart (the heart is...