Biology Edexcel iGCSE 1a-2b

autotrophic

nutrition in which organism makes its own organic food from inorganic substances

heterotrophic

nutrition in which organism obtains organic food from other organisms

saprotrophic

nutrition in which organism secretes digestive enzymes onto dead or decaying material and absorbs soluble products

eukaryotic

organism whose cells contain a nucleus and membrane-bound organelles

prokaryotic

organism whose cells lack a nucleus and membrane-bound organelles

protoctist

mainly single-celled eukaryotic organism that does not fit into plant animal or fungal groups

pathogen

microorganism or agent that causes disease

parasitic

living on or inside another organism and obtaining nutrients from it

mycelium

network of fungal hyphae

hyphae

thread-like structures forming most fungi

extracellular digestion

digestion occurring outside cells after digestive enzymes are secreted

plasmid

small circular DNA molecule found in bacteria

circular chromosome

circular DNA molecule containing most bacterial genetic material

nucleic acid

molecule such as DNA or RNA that carries genetic information

organelle

specialised structure inside cell with particular function

level of organisation

hierarchy of organelles cells tissues organs and organ systems

tissue

group of similar cells working together to perform a function

organ

structure made from different tissues working together to perform a function

organ system

group of organs working together to perform a major body function

cell differentiation

process by which cell develops specialised structures and functions

specialised cell

cell adapted to perform a particular function

vacuole

fluid-filled space containing cell sap that helps maintain pressure inside plant cell

cell wall

rigid cellulose layer outside cell membrane that supports and strengthens plant cell

cellulose

carbohydrate forming plant cell walls

chitin

substance forming fungal cell walls

glycogen

carbohydrate used for energy storage in animals and fungi

starch

carbohydrate used for energy storage in plants

give examples of plants

Examples include flowering plants like maize and herbaceous legumes like peas or beans

give examples of protists

amoeba-->lives in pond water + has features of animal cell

chlorella-->has chloroplasts + is more like plants

plasmodium-->pathogen that causes malaria

give examples of fungi

yeast--> single-celled

mucor--> has typical hyphal structure

give examples of bacteria

lactobacillus bulgaricus-->used in production of yoghurt pneumococcus-->pathogen that causes pneumonia

give examples of viruses

TMV-->causes discoloring of leaves of tobacco plants by preventing formation of chloroplasts

influenza--> causes 'flu'

HIV--> causes AIDS

stem cell

unspecialised cell that can divide by mitosis and develop into more stem cells or cells that go on to differentiate to become specialised cells

difference between adult stem cells and embryonic stem cells

embryonic --> differentiate into EVERY type of cell

adult --> found in the bone marrow + only differentiate into blood cells

state the function of a red blood cell

transport oxygen around the body

State the adaptations of a red blood cell

-has a biconcave shape-->higher surface area-->can carry more oxygen + easily move through blood vessels

-has protein haemoglobin-->transports oxygen from lungs to body

State the function of a root hair cell

absorb water and minerals from the soil

State adaptations of root hair cells

-large surface area-->increases rate of absorption

-lots of mitochondria-->releases energy for glucose during respiration-->providing more energy for active transport

State the function of sperm cells

to carry male genetic material to egg cell to fertilise it and create a zygote

state adaptations of sperm cells

-acrosome in the head contains digestive enzymes to penetrate the egg cell membrane

-midpiece has tons of mitochondria for respiration to release energy needed to swim and fertilise the egg

-tail enables sperm to swim

State the function of a palisade cell

carry out photosynthesis using energy from sunlight

state adaptations of palisade cells

-lots of chloroplasts-->absorb as much light energy possible

-tall and thin shape-->large surface area to catch light

advantages of stem cells in medicine

-embryonic stem cells can differentiate into any cell type

-can differentiate into specialized cells to replace damaged tissue

-adult stem cells (like bone marrow transplants) are used to treat blood conditions such as leukemia and anemia

-using a patient's own stem cells avoids immune rejection

why is it advantageous to use a patient's own stem cells in medicine?

cells formed from these stem cells will have the same genes + antigens as the patient --> no rejection by patient's body-->no need for patient to take immunosuppressant drugs to prevent immune response towards the cell

What is nutrition?

Taking in materials for energy, growth and development.

What is respiration?

series of chemical reactions in cells that release energy from glucose

What is excretion?

Removal of toxic materials and waste products of metabolism.

What is sensitivity?

Detecting and responding to changes(stimuli) in the INTERNAL or EXTERNAL environment

What is homeostasis?

Regulation of internal conditions to maintain optimum conditions for cells.

Give three examples of conditions controlled by homeostasis.

Body temperature, blood glucose concentration and water content.

Why is controlling body temperature important?

maintains optimum enzyme activity; extreme temperatures can denature enzymes

Why must blood glucose be regulated?

cells need glucose for respiration; excessively high glucose can damage blood vessels and organs

Why is water content regulated?

Maintains water balance in cells and prevents excessive water gain or loss.