Biology unit 1 - area of study 2 outcome 2

What are the main types of vascular plant tissues?

• Xylem – transports water and minerals from roots to leaves.

• Phloem – transports sugars and nutrients produced in photosynthesis around the plant.

How does xylem transport water?

Through transpiration pull: water evaporates from leaves, creating negative pressure that draws more water upward through the xylem vessels.

How does phloem transport nutrients?

Through translocation – sugars move from areas of high concentration (source, e.g. leaves) to areas of low concentration (sink, e.g. roots or fruits).

How are vascular tissues arranged in different parts of a plant?

• Roots: Xylem in the centre for stability.

• Stems: Xylem and phloem form vascular bundles for support and efficient transport.

• Leaves: Veins containing xylem and phloem distribute water and food.

What are stomata and guard cells?

• Stomata are pores on the leaf surface that control gas exchange.

• Guard cells open and close the stomata to regulate water loss and CO₂ intake.

What is the role of root hairs in plants?

Root hairs increase the surface area for water and mineral absorption from the soil, enhancing the plant’s ability to take up nutrients efficiently.

How do plants minimise water loss?

• Closing stomata during hot or dry conditions.

• Waxy cuticle on leaves to prevent evaporation.

• Small leaf surface area in arid plants.

What is cell specialisation in animals?

Cell specialisation (differentiation) is when cells develop specific structures and functions suited to their roles — e.g. red blood cells for oxygen transport, neurons for signalling.

What are tissues, organs, and systems?

• Tissues: Groups of similar cells (e.g. muscle, epithelial).

• Organs: Structures made of different tissues (e.g. stomach, heart).

• Systems: Groups of organs working together (e.g. digestive system).

What is the main function of the digestive system?

To break down food into nutrients that can be absorbed into the bloodstream for energy, growth, and repair.

What is the main function of the endocrine system?

To produce and secrete hormones that regulate processes like growth, metabolism, and reproduction.

What is the main function of the excretory system?

To remove metabolic waste (e.g. urea, carbon dioxide) and maintain the body’s water and salt balance.

How does organ structure relate to function?

Each organ’s shape and tissue composition suits its role — e.g. the villi in intestines increase surface area for absorption, alveoli in lungs maximise gas exchange.

How do animal systems work together to maintain homeostasis?

Systems interact to keep internal conditions stable — e.g.

• The endocrine and nervous systems regulate temperature and blood sugar.

• The excretory system removes wastes to keep pH and water levels balanced.

What is homeostasis?

The process of maintaining stable internal conditions (like temperature, pH, and glucose levels) despite external changes.

What is transpiration?

Transpiration is the loss of water vapour from leaves through stomata. It helps pull water upward from roots via the xylem, maintaining nutrient and water transport.

What is the role of xylem and phloem?

• Xylem: Transports water and minerals upward from roots to leaves.

• Phloem: Transports sugars (glucose) and nutrients throughout the plant.

How do stomata regulate water loss?

Guard cells open stomata to allow gas exchange and close them to prevent excess water loss, depending on environmental conditions.

What environmental factors affect transpiration?

• Temperature (higher = faster transpiration)

• Humidity (higher = slower transpiration)

• Wind (increases water loss)

• Light intensity (opens stomata for photosynthesis)

Why is transpiration important for plants?

It enables cooling, water transport, and nutrient distribution, maintaining the plant’s water balance.

What are feedback mechanisms?

Feedback mechanisms are biological processes that detect and respond to changes.

• Negative feedback restores balance (e.g., lowering blood sugar).

• Positive feedback enhances a process (e.g., contractions during childbirth).

What is the role of the liver, pancreas, kidneys, and hypothalamus in regulation?

• Liver: Stores and releases glucose; detoxifies blood.

• Pancreas: Produces insulin and glucagon to regulate blood glucose.

• Kidneys: Control water balance and waste removal.

• Hypothalamus: Monitors internal conditions and coordinates temperature and hormone responses.

How does the stimulus–response model work?

1. Stimulus: Change detected (e.g., high temperature).

2. Receptor: Senses change (e.g., thermoreceptors).

3. Control centre: Processes information (e.g., hypothalamus).

4. Effector: Carries out response (e.g., sweat glands).

5. Response: Condition returns to normal.

What is thermoregulation?

The control of body temperature to maintain an optimal internal range (around 37°C in humans) using mechanisms like sweating, shivering, and blood vessel dilation/constriction.

How is blood glucose regulated?

• Insulin (from pancreas) lowers blood glucose by promoting glucose uptake and glycogen storage.

• Glucagon raises blood glucose by breaking down glycogen into glucose.

How is water balance maintained in animals?

The kidneys regulate water via osmosis and hormone control (ADH), ensuring correct hydration and solute balance.

What causes Type 1 Diabetes?

The immune system destroys insulin-producing cells in the pancreas, preventing glucose uptake and leading to high blood sugar (hyperglycaemia).

What are symptoms of Type 1 Diabetes?

Fatigue, increased thirst, frequent urination, and weight loss due to inability to use glucose for energy.

What is hypoglycaemia?

A condition of low blood sugar levels caused by excess insulin or insufficient food intake. It can lead to dizziness, confusion, and even coma if untreated.

What is hyperthyroidism?

Overproduction of thyroid hormones, leading to increased metabolism, rapid heartbeat, weight loss, and anxiety.

Why are homeostatic failures dangerous?

They disrupt critical body functions like temperature control, energy use, and water balance — which can result in organ failure or death if untreated.