combined science ht p1 biology

Contains DNA to control the cell

What is the function of the nucleus?

Controls entry and exit of substances

What is the function of the cell membrane?

Provides structure and support

What is the function of the cell wall?

Carry out respiration to release energy

What is the function of mitochondria?

Protein synthesis

What is the function of ribosomes?

Carry out photosynthesis

What is the function of chloroplasts?

Contains cell sap

What is the function of a vacuole?

A cell that does not have a nucleus

Define a prokaryote

A cell that has DNA in a nucleus

Define a eukaryote

Nucleus, mitochondria, chloroplasts

Name two cell structures that are in a eukaryote but not in a prokaryote

A small loop of DNA in bacteria

What is a plasmid?

Cellulose

What is a plant cell wall made from?

As a single, free-floating loop; also on plasmids

How is DNA stored in a bacterial cell?

The process by which cells become specialised

What is differentiation?

Magnification \= Image Size ÷ Actual Size

What is the equation for magnification?

0.0136mm, or 13.6µm

A photograph of a cell is 15mm long. It has a magnification of 1100x. What is the actual size?

5400µm, or 5.4mm

A cell is 12µm wide. It is magnified by 450 times. How big is the image?

6000 times

If the image of a virus is 1.2mm, and its actual size is 0.2µm, how much has it been magnified by?

38.5mm

Convert 38500µm into mm

1000

How many µm are in 1mm?

1.74 x 10^4 m

Write 17400m in standard form

3.4 x 10^-3

Write 0.0034 in standard form

It has a tail to swim to the egg

How is a sperm cell adapted for its function?

It has a long axon to conduct impulses over long distances

How is a nerve cell adapted for its function?

It can contract to cause movement

How is a muscle cell adapted for its function?

It has a large surface area to increase osmosis of water

How is a root hair cell adapted for its function?

It has hollow ends to transport water

How is a xylem cell adapted for its function?

It has sieve tubes to transport sugars

How is a phloem cell adapted for its function?

An undifferentiated cell that can differentiate to become any type of specialised cell

What is a stem cell?

In embryos and in bone marrow

Where are stem cells most commonly found in animals?

Plant tissue containing stem cells

What is meristem tissue?

Throughout the whole life of the plant

When are plant cells able to differentiate?

At an early stage of development (as an embryo)

When do most animal cells differentiate?

Resolution is the smallest distance between two separate points

What is the "resolution" of a microscope?

They have a higher resolution and higher magnification

Why are electron microscopes better than light microscopes?

Ribosomes

Give an example of an organelle you could see with an electron microscope, but not with a light microscope?

Double helix

What shape is DNA?

Chromosomes

What molecule is DNA stored as?

In pairs

How are chromosomes usually found in body cells?

A small section of DNA that codes for a specific protein

What is a gene?

Cell division

What is mitosis?

To grow and to replace cells

What are the two main purposes of mitosis?

It must replicate its DNA to form two copies of each chromosome

What must happen in a cell before mitosis can take place?

One set of chromosomes is pulled to each end of the cell and the nucleus divides

Once DNA has been replicated, what happens next in mitosis?

Two genetically identical daughter cells

What are the products of mitosis?

The stages in a cell as it grows and goes through mitosis

What is the cell cycle?

Diabetes and paralysis

What conditions may stem cells be able to help with?

From stem cells in bone marrow

How are most blood cells formed?

When an embryo is produced with the patient's genes so that stem cells from the embryo can be used

What is therapeutic cloning?

They contain the same genes as the patient, so are not rejected by the patient's body

Why are stem cells made by therapeutic cloning more useful for medical treatments?

For preventing the extinction of rare plant species, and for producing large numbers of identical disease-resistant crops

Give two ways using stem cells to clone plants may be useful

The movement of particles from a high concentration to a low concentration down a concentration gradient

Define diffusion

Temperature, surface area, difference in concentration

What factors affect the rate of diffusion?

There are lots of villi to give a large surface area, villi contain lots of capillaries close to the surface so there is a short diffusion distance

How is the small intestine adapted for diffusion?

Lots of alveoli give a large surface area, they have thin walls and capillaries are close so there is a short diffusion distance

How are the lungs adapted for diffusion?

Gills have lots of filaments to give a large surface area, there are lots of capillaries with a short distance for diffusion

How are fish gills adapted for diffusion?

Roots have lots of long root hair cells to give a large surface area for osmosis

How are plant roots adapted to absorb water?

Root hair cells have mitochondria to release energy for active transport of mineral ions

How are plant roots adapted to absorb mineral ions?

Leaves have lots of stomata on the underside to allow carbon dioxide to diffuse in

How are leaves adapted for gas exchange?

The movement of water from a high water potential to a low water potential across a partially permeable membrane

Define osmosis

(Change in mass ÷ Starting mass) x 100

How would you calculate % change in mass of a potato chip in sucrose solution?

To remove excess water, so it doesn't increase the mass

Why should you blot a potato chip dry before taking its mass?

So that you can compare different chips, as the starting mass of each potato may not be the same

Why do you calculate %change in mass of a potato chip rather than just change in mass?

The movement of particles from a low concentration to a high concentration against a concentration gradient, using energy

Define active transport

Absorption of mineral ions in root hair cells

Explain one example of active transport in plants

Absorption of glucose in the small intestine

Explain one example of active transport in animals

A group of cells with similar structure and function

Define a tissue

A group of tissues working together to perform a function

Define an organ

A group of organs working together

Deine an organ system

Epithelial tissue, muscle tissue, nerve tissue, glandular tissue

Give two examples of tissues in animals

Palisade tissue, spongy mesophyll tissue, xylem tissue, phloem tissue

Give two examples of tissues in plants

Heart, lungs, stomach, brain, liver

Give two examples of organs in animals

Leaf, root, stem, flower

Give two examples of organs in plants

A biological catalyst that carries out metabolic reactions in living organisms

Define an enzyme

A substance that is broken down by an enzyme

What is a substrate?

Active site

Where does a substrate bind to an enzyme?

Enzyme-substrate complex

What is formed when an enzyme binds to a substrate?

Each type of enzyme has an active site that only fits one specific substrate

Why are enzymes specific?

Protein

What are enzymes made of?

High temperatures or pH that is too high or low

What conditions cause enzymes to denature?

When an enzyme cannot work because its active site has lost its specific shape so the substrate no longer fits

Define denature

37oC

What is human body temperature?

A substrate is specific to one enzyme because of the specific shape of its active site (like a key fitting a lock)

What is the Lock and Key Theory?

To break large, insoluble molecules into small, soluble molecules so they can be absorbed

What is the purpose of digestion

Salivary glands and pancreas

Where is amylase made?

Stomach and small intestine

Where is protease made?

Pancreas and Small intestine

Where is lipase made?

Starch

What is the substrate of amylase?

Protein

What is the substrate of protease?

Lipids (fats)

What is the substrate of lipase?

Carbohydrate

What is the substrate of carbohydrase?

Glucose

What are the products of amylase digesting starch?

Amino acids

What are the products of protease digesting proteins?

Glycerol and fatty acids

What are the products of lipase digesting lipids?

Liver

Where is bile made?

Gall bladder

Where is bile stored?

To emulsify fats, and to neutralise stomach acid

Give two functions of bile

To break large fats into small droplets, to increase surface area for lipase

What is the purpose of emulsification

So that enzymes aren't denatured

Why must hydrochloric acid from the stomach be neutralised by bile in the small intestine?

Water bath

What equipment is used to control temperature in an investigation?