Biology Term 1 Year 11

Root hair cell

A specialised epidermal cell on roots with a long projection that increases surface area to absorb water and mineral ions from soil

What is plant tissue made from

organized groups of specialized plant cells working together to perform specific functions like growth, protection, support, and transport.

Plant organ

A structure composed of multiple tissues that work together to perform a specific function

Organ system (plant)

A group of organs working together to carry out major functions within the plant

Root system

The part of the plant that anchors the plant in soil and absorbs water and mineral nutrients

Leaf

The main photosynthetic organ that produces glucose, allows gas exchange, and regulates water loss

Plant excretion

The removal of metabolic wastes such as oxygen, water vapour, mineral salts, or resins into the environment

Xylem

Vascular tissue that transports water and dissolved minerals from the roots to the rest of the plant

Phloem

Vascular tissue that transports sugars and organic nutrients throughout the plant in both directions

Vessel elements

Dead hollow xylem cells joined end-to-end for efficient water transport

Tracheids

Long narrow xylem cells that assist water transport and provide structural support

Sieve tube elements

Living specialised phloem cells connected end to end that conduct movement of sugars

Companion cells

Cells associated with sieve tube elements that provide metabolic support and help load or unload sugars

Phloem sap

The nutrient

Vascular bundle

A structure in plants containing both xylem and phloem tissues

Transport in plants

The movement of water, gases, and nutrients throughout the plant

Diffusion

Passive movement of molecules from a region of high concentration to a region of low concentration

Osmosis

The diffusion of water across a selectively permeable membrane from high water concentration to low

Active transport

Movement of substances across membranes using energy from ATP against a concentration gradient

Transpiration

The loss of water vapour from the aerial parts of plants, mainly through stomata in leaves

Transpiration stream

The continuous flow of water from roots to leaves through the xylem driven by transpiration

Cohesion

The attraction between water molecules that helps maintain a continuous column of water in the xylem

Adhesion

The attraction between water molecules and the walls of xylem vessels that assists upward water movement

Root pressure

Pressure generated by osmotic water uptake in root cells that helps push water into the xylem

Stomata

Microscopic pores in the leaf epidermis that regulate gas exchange and water loss

Guard cells

Two specialised cells surrounding each stoma that control opening and closing through changes in turgor pressure

Turgor pressure

Pressure created by water inside plant cells that keeps them firm and allows stomata to open

Gas exchange in plants

The diffusion of carbon dioxide into the plant and oxygen out of the plant through specialised surfaces

Lenticels

Small openings in woody stems that allow gas exchange between internal tissues and the atmosphere

Plant adaptations for gas exchange

Structural features such as stomata, lenticels, and root hairs that allow efficient diffusion of gases

Bryophyte gas exchange explanation

Mosses and similar plants exchange gases directly across their entire moist body surface

Pneumatophores

Specialised aerial roots in mangroves that allow oxygen uptake in waterlogged soils

Xerophyte adaptations

A plant adapted to dry environments with structures that reduce water loss such as minimal leaves and stomata opening at night. Cacti cuticles are specialised layers that minimise water loss.

Halophyte adaptations

A plant adapted to high salinity environments where salt levels influence water movement, such as excretion of salt through glands

Photosynthesis

plant process that converts water and carbon dioxide into glucose and oxygen in the presence light energy and chlorphyll

Photosynthesis equation

Carbon dioxide and water are converted into glucose and oxygen using light energy

Chloroplast

The organelle in plant cells where photosynthesis occurs

Grana

Stacks of thylakoid membranes in chloroplasts where light

Stroma

fluid-filled space within the inner membrane of a chloroplast, surrounding the grana (thylakoids)

Light dependent reactions

initial stage of photosynthesis occurring in the thylakoid membranes of chloroplasts, where light energy is absorbed by chlorophyll and converted into chemical energy (ATP and NADPH)

Photolysis of water

the chemical process by which water molecules are broken down into hydrogen ions, electrons, and oxygen gas during light-dependent phase

ATP production in photosynthesis

Light energy drives the formation of ATP which stores energy for later reactions

Light independent reactions (Calvin–Benson cycle)

the second stage of photosynthesis, occurring in the chloroplast stroma, which uses ATP and NADPH produced by light-dependent reactions to convert CO2 into glucose.

Carbon fixation

The process in the Calvin cycle where carbon dioxide is incorporated into organic molecules such as glucose

Glucose

a simple sugar which is an important energy source in living organisms

Metabolism

The total of all chemical reactions occurring within a living organism

Anabolism

Metabolic reactions that build complex molecules from simpler molecules using energy

Catabolism

Metabolic reactions that break down complex molecules into simpler molecules releasing energy

ATP

(adenosine triphosphate) - the primary energy carrier molecule which fuels essential cellular activities like photosynthesis, nutrient uptake, and growth

ATP structure

a nitrogenous base (adenine), a ribose sugar and three phosphate groups

ATP hydrolysis

The breakdown of ATP into ADP and phosphate releasing energy for cellular processes

Mitochondria

Organelles where aerobic respiration occurs

Glycolysis

The first stage of respiration occurring in the cytoplasm where one glucose molecule forms two pyruvate and produces 2 ATP

What is pyruvate in biology

Pyruvate is the a product of glycolysis, which is either converted into acetyl Coa in aerobic respiration or fermented into lactate/ethanol/carbon dioxide in anaerobic respiration.

Krebs cycle

A stage of aerobic respiration occurring in the mitochondrial matrix where pyruvate is broken down releasing carbon dioxide and producing ATP

Electron transport chain

The final stage of aerobic respiration occurring in the mitochondrial cristae where most ATP is produced and water forms

Cristae

The folded inner membranes of mitochondria where the electron transport chain occurs

Aerobic respiration equation

Glucose + oxygen → carbon dioxide + water + ATP energy

Anaerobic respiration

The breakdown of glucose without oxygen producing much less ATP

Fermentation

a metabolic process by which cells break down glucose to produce energy (ATP) in the absence of oxygen. byproducts include ethanol, carbon dioxide, and lactic acid, depending on the type of fermentation

Lactic acid fermentation

Anaerobic respiration in animals where pyruvate is converted into lactic acid

Alcoholic fermentation

Anaerobic respiration in plants and fungi where pyruvate forms ethanol and carbon dioxide

Energy yield of aerobic respiration

Approximately 36–38 ATP molecules produced from one glucose molecule

Energy yield of anaerobic respiration

Only 2 ATP molecules produced from one glucose molecule

Comparison of aerobic and anaerobic respiration

Both begin with glycolysis in the cytoplasm but aerobic respiration requires oxygen and continues in mitochondria producing much more ATP, while anaerobic respiration occurs only in the cytoplasm and produces lactic acid or alcohol with much less energy

Factors affecting transpiration rate

Light intensity, temperature, wind speed, humidity, and soil water availability humidity increase, transpiration decrease.

Stem cells

biological cells found in multicellular organisms that possess two unique, defining properties: they can self-renew (divide to produce more stem cells) and differentiate (develop into specialized, mature cell types like blood, nerve, or muscle cells).

Self renewal

The ability of stem cells to continuously divide and produce identical copies of themselves through mitosis.

Potency

The capacity of a stem cell to differentiate into different specialised cell types.

Embryonic stem cells

Stem cells found in early embryos that can differentiate into almost all cell types in the body.

Adult stem cells

Stem cells found in mature tissues that can divide and produce a limited range of specialised cell types for growth and repair.

Cell cycle

The sequence of stages a cell goes through to grow, replicate its DNA, and divide into two daughter cells.

Interphase

The stage of the cell cycle where the cell grows, carries out normal functions, replicates DNA

Mitosis

The process of nuclear division that produces two genetically identical daughter cells.

Prophase

The stage of mitosis where chromosomes condense, the nuclear membrane begins to break down, and spindle fibres form.

Metaphase

The stage of mitosis where chromosomes line up at the metaphase plate of the cell attached to spindle fibres.

Anaphase

The stage of mitosis where sister chromatids separate and move to opposite poles of the cell.

Telophase

The stage of mitosis where chromosomes arrive at the poles and new nuclear membranes begin to form.

Cytokinesis

The division of the cytoplasm that results in two separate daughter cells.

Cambium

A layer of plant stem cells in stems and roots that divide to produce new vascular tissues for growth.

Plant embryo differentiation

The process by which cells of a developing plant embryo become specialised tissues through the activity of apical meristems.

Ground tissue

Plant tissue that performs functions such as photosynthesis, storage, and support.

Vascular tissue

Plant tissue responsible for transport of water, minerals, and sugars through xylem and phloem.

Epidermis (plant)

The outer protective layer of plant cells that reduces water loss and protects internal tissues.

Unicellular organism

An organism made of a single cell that performs all life functions within that cell.

Multicellular organism

An organism composed of many specialised cells organised into tissues, organs, and systems.

Prokaryotic cells

Simple cells without a nucleus or membrane

Eukaryotic cells

Cells containing a nucleus and membrane

Cell specialisation

The process where cells develop structures and functions suited to specific roles in a multicellular organism.

Gametes

Specialised reproductive cells such as sperm and eggs involved in sexual reproduction.

Stages of multicellular organism formation

The four processes required to form multicellular organisms: proliferation, specialisation, interaction, and movement.

Proliferation

The rapid division of cells to produce many cells with identical genetic information.

Specialisation

The process by which cells develop specific structures and functions.

Identify ways that cells can work together and communicate

cells communicate by sending chemical signals, through hormones, nerves, plasmodesmata, and physical connection such as a gap junction between cells

Cell movement

The movement of cells to correct positions during development so they are surrounded by supporting cells.

Plasmodesmata

Microscopic channels between plant cells that allow direct transport and communication between neighbouring cells.

Cell communication in plants

The transfer of signals and materials between plant cells through plasmodesmata.

Phototropism

The growth response of plants where shoots grow toward light due to unequal distribution of growth hormones.

Totipotent stem cell + example

capable of differentiating into any cell type in the body, including extra embryonic tissues Example is placenta