Cells, Diffusion And Active Transport (T1) Flashcards Preview

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Flashcards in Cells, Diffusion And Active Transport (T1) Deck (30):

What is the name of the living material that makes up a cell?



What are organelles?

Specialised structures within a cell, held within the cytoplasm.


Describe the function of a cell's nucleus..

The nucleus is the largest organelle in a cell.

Almost all cells have a nucleus and those that don't are usually dead or don't live very long.

The nucleus contains chromosomes which carry the genetic material - genes - which will control the activities of the cell.


How do genes control the activities of a cell?

By determining which proteins the cell can make.


What are the mitochondria?

Most of the energy released from respiration is released in the mitochondria.


Which type of cells may require the mitochondria to release large amounts of energy?

- muscle cells
- nerve cells


What are seven organelles found in a typical plant cell?

- cell wall
- cell membrane
- chloroplasts
- mitochondria
- cytoplasm
- vacuole
- nucleus


What are three organelles that are found in both animal and plant cells?

- cell membrane
- mitochondria
- nucleus


Name three organelles that are found in ONLY plant cells..

- cell wall
- vacuole
- chloroplasts


What is the cell wall in a plant cell?

A layer or non-living material found just outside the cell membrane of plant cells.

It is made mainly of a carbohydrate called cellulose.


What is the function of the cell wall in a plant cell?

Plant cells absorb water, producing internal pressure which pushes against other cells of the plant, giving support.

Without the cell wall to withstand the pressure, this method of support would not be possible.

The cell wall contains large holes to allow water and other dissolved substances to pass.


The cell wall of a plant is known as ....... permeable.

Freely permeable.


What is cellulose and how does it affect the shape of plant cells?

Cellulose is a tough carbohydrate that helps plant cells maintain a fairly fixed shape.


What is the vacuole in a plant cell?

The vacuole is often found in mature plant cells.

It is a large central space surrounded by a membrane.

It is filled with a watery substance called cell sap, a store of dissolved sugars, mineral ions and other solutes.


Cell sap in the vacuole of a plant cell helps keep the cell ......



What are chloroplasts?

Organelles in plant cells that absorb light energy to make food by process of photosynthesis.

They are only present in the green parts of the plant.

They are green as they contain the green pigment chlorophyll.


What is diffusion in cells and when does it occur?

Diffusion occurs when a substance is more concentrated in one place than another.

The difference in concentration is called a concentration gradient.


Diffusion is the ...... ....... of particles from a region of ..... ........ to a region of ...... .......

Diffusion is the net movement of particles from a region of high concentration to a region of low concentration.


Why is the rate of diffusion greater at higher temperatures?

Because diffusion happens because of the kinetic energy of the particles and at higher temperatures particles have more kinetic energy.


What is active transport in cells?

When a cell needs to take in a substance when there is very little of that substance outside the cell.


When particles diffuse they are said to be working down a ......

Concentration gradient


When a cell has to carry out active transport, particles are moving ......

Against a concentration gradient.


How does a cell get the energy needed to carry out active transport?

The energy is released through respiration.


Biologists speak of a cell ....... ions or molecules in and out of the cell and the ....... are large ........ molecules located in the ...... ........

Biologists speak of a cell pumping ions or molecules in and out of the cell and the pumps are large protein molecules located in the cell membrane.


Give an example of active transport in the human body...

In the human small intestine some glucose in the gut is absorbed into the cells lining the intestine by active transport.


What are five organelles you will find in a typical animal cell?

- cell membrane
- nucleus
- mitochondria
- cytoplasm
- ribosomes


Name three factors that can increase the rate of diffusion..

- a steep concentration gradient
- high temperatures
- a large surface area to volume ratio


Explain what is meant by a cell membrane being partially permeable and why this is important to osmosis..

Osmosis can only take place if the cell membrane is permeable to water but not other solutes.

This is known as partially permeable.


Briefly describe the process of mitosis and what controls it...

- multicellular organisms begins life as a single fertilised egg called a zygote
- the chromosomes in the nucleus are copied
- the nucleus splits in two and the genetic information is shared between these 'daughter cells'
- the cytoplasm then divides forming two smaller cells
- these take in food substances to supply energy and building materials so they can grow to full size
- the process is repeated until an embryo is formed
- this type of cell division is called mitosis
- it is under control of the genes


Briefly explain what cell differentiation is and what controls it...

The process of cell division / mitosis is repeated and as the embryo grows, cells become specialised to carry out particular roles.

This specialisation is known as differentiation as is under control of the genes.

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