Cells, Diffusion And Active Transport (T1)

Question 1

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

Answer 1

Cytoplasm

Question 2

What are organelles?

Answer 2

Specialised structures within a cell, held within the cytoplasm.

Question 3

Describe the function of a cell’s nucleus..

Answer 3

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.

Question 4

How do genes control the activities of a cell?

Answer 4

By determining which proteins the cell can make.

Question 5

What are the mitochondria?

Answer 5

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

Question 6

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

Answer 6

• muscle cells

- nerve cells

Question 7

What are seven organelles found in a typical plant cell?

Answer 7

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

Question 8

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

Answer 8

• cell membrane
• mitochondria
• nucleus

Question 9

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

Answer 9

• cell wall
• vacuole
• chloroplasts

Question 10

What is the cell wall in a plant cell?

Answer 10

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

It is made mainly of a carbohydrate called cellulose.

Question 11

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

Answer 11

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.

Question 12

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

Answer 12

Freely permeable.

Question 13

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

Answer 13

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

Question 14

What is the vacuole in a plant cell?

Answer 14

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.

Question 15

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

Answer 15

Turgid

Question 16

What are chloroplasts?

Answer 16

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.

Question 17

What is diffusion in cells and when does it occur?

Answer 17

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

The difference in concentration is called a concentration gradient.

Question 18

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

Answer 18

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

Question 19

Why is the rate of diffusion greater at higher temperatures?

Answer 19

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

Question 20

What is active transport in cells?

Answer 20

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

Question 21

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

Answer 21

Concentration gradient

Question 22

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

Answer 22

Against a concentration gradient.

Question 23

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

Answer 23

The energy is released through respiration.

Question 24

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

Answer 24

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.

Question 25

Give an example of active transport in the human body…

Answer 25

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

Question 26

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

Answer 26

• cell membrane
• nucleus
• mitochondria
• cytoplasm
• ribosomes

Question 27

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

Answer 27

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

Question 28

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

Answer 28

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

This is known as partially permeable.

Question 29

Briefly describe the process of mitosis and what controls it…

Answer 29

• 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

Question 30

Briefly explain what cell differentiation is and what controls it…

Answer 30

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.