Biology Unit 1 Exam

Prokaryotic vs eukaryotic cells

Prokaryotic cells lack a nucleus and membrane-bound organelles, whereas eukaryotic cells have both a nucleus and organelles, allowing for more complex structures.

Cell size and surface area to volume ratio

Material exchange occurs on the surface.

Effective exchange occurs when the volume is lower than surface. The smaller the cube the greater SA:V ratio.

Small intestines contain villi and microvilli to increase nutrient absorption

Red blood cells are flattened in shape for gas exchange.

Animal Cells

Lysosomes: Contains enzymes that break down waste.

Centrosomes: Involved in cell division and organisation of the cytoskeleton.

Shared Organelles

• Mitochondria

• Nucleas

• Endoplasmic Reticulum

• Golgi Apparatus

• Ribosomes

• Vesicles

• Cytoplasm

• Cell membrane

Plant Cells

Chloroplasts: Site for photosynthesis

Cell Wall: Outer layer providing protection and maintaining structure

Large Central Vacuole: storage and help maintaining pressure

The structure and function of the plasma membrane

The plasma membrane, a phospholipid bilayer, regulates the movement of substances into and out of cells through various transport mechanisms. It's composed of hydrophilic heads and hydrophobic tails, which dictate permeability.

Water, hydrophilic molecules, and hydrophobic molecules utilize different pathways, including osmosis, facilitated diffusion, and active transport.

Binary Fission

Binary fission is the primary method of cell division and asexual reproduction in prokaryotic cells, such as bacteria and archea.

• DNA replication

• Cell elongation

• Septum formation

• Septum formation

• Daughter Cell Separation

The eukaryotic cell cycle, including the characteristics of each of the sub-phases of mitosis and cytokinesis in plant and animal cells

Interphase:

• G1: Cell grows

• S: Dna replication occurs

• G2: Continues growth and prepares for mitosis

Mitosis

Prophase

Pro-metaphase

Metaphase

Anaphase

Telophase

Cytokinesis

Apoptosis

Apoptosis, or programmed cell death, is a highly regulated process in multicellular organisms where cells are eliminated in a controlled manner. Apoptosis plays crucial roles in development, tissue homeostasis, and immune function.

Disruptions to Cell Cycle

The cell cycle is a carefully controlled process that makes sure cells grow and divide correctly. It has checkpoints to check for problems before moving to the next step.

In cancer, cells often ignore these checkpoints because of mutations in certain genes, like those for cyclins and cyclin-dependent kinases (CDKs), which help control cell division. This leads to uncontrolled cell growth and the formation of tumors.

Mutations can also damage genes that repair DNA. When this happens, more genetic mistakes build up, making the cancer worse. A common example is a mutation in the p53 gene, which normally helps stop the cell cycle or cause damaged cells to die.

Characteristics of cancer cells

• Uncontrolled growth and division

• Ability to invade and metasize

Specialization and organization of plant cells into tissues for specific functions in vascular plants, including intake, movement and loss of water.

• Xylem: Transport water and minerals from root to rest of the plant

• Phloem: Transports sugars and nutrients produced during photosynthesis from the leaves to the rest of the plant.

• Root hairs: Located on the outer surface of roots, increases surface area

• Leaf Tissues: Optimizes light absorption and gas exchange. Waxy cuticle helps regulate water loss through transpiration

Water movement in plants

Water Movement in Vascular Plants: 

1. 1. Absorption:

   Water is absorbed from the soil by root hair cells, primarily through osmosis. 

2. 2. Uptake:

   The absorbed water is then transported through the xylem to the rest of the plant. 

3. 3. Transpiration:

   Water is lost from the leaves through stomata, which are pores regulated by guard cells. 

4. 4. Water Circulation:

   The movement of water in the xylem is driven by transpiration pull and cohesion-tension forces, which create a continuous column of water from the roots to the leaves

specialisation and organisation of animal cells into tissues, organs and systems with specific functions of the digestive and endocrine system

Animal cells differentiate and organize into tissues, organs, and systems to perform specific functions. The digestive system breaks down food and absorbs nutrients, while the endocrine system uses hormones to regulate bodily functions. These systems work together to maintain homeostasis and ensure the survival of the organism

Regulation of water balance in vascular plants

Vascular plants regulate water balance through stomatal control, transpiration, and water uptake and transport.

Regulation of body temperature and blood glucose in animals by homeostatic mechanisms, including stimulus-response models, feedback loops and associated organ structures.

Stimulus-Response Model

Homeostatic regulation requires systems to detect and respond to internal and external changes via a stimulus-response pathway

• A stimulus is a change in the environment (either external or internal) that is detected by a receptor

Negative feedback loops:

• Reduce the change or reverse it (blood sugars too high)

Positive feedback loops:

• Reinforces the change (contractions strengthening until birth)

Malfunctions in homeostatic mechanisms: type 1 diabetes, hypoglycaemia, hyperthyroidism.

• Type 1 diabetes: is a failure in insulin production, disrupting glucose regulation. 

• Hypoglycemia: is a state of abnormally low blood sugar, often linked to diabetes but can occur independently. 

• Hyperthyroidism: involves excessive thyroid hormone production, which can interfere with glucose metabolism and lead to imbalances. 

Biological science concepts specific to the selected scientific investigation and their significance, including the definition of key terms 

• Variables (independent, dependent, controlled)

• Hypothesis

• Scientific method

• Accuracy

• Precision

• Reliability

• Validity

• Errors

Techniques of primary qualitative and quantitative data

Qualitative

• Interviews

• Focus groups

Quantitative

• Surveys

• Experiments

Primary data characteristics

• Primary data is collected directly from the source, making it original and not previously analyzed or interpreted by others.