bio 1 general (p)

Question 1

Diffusion is

Answer 1

the passive movement of substances down a concentration gradient.

Question 2

Osmosis is

Answer 2

a special case of diffusion in which water moves from a solution of higher water potential to a solution of lower water potential through a partially permeable membrane.

Question 3

What does TEM stand for?

Answer 3

Transmission Electron Microscope

Question 4

What organelles make up an epithelial cell found in the small intestine? These organelles can not have been seen using an optical (light) microscope. Explain why.

Answer 4

Nucleus (nucleolus, double membrane, chromatin), mitochondria, ribosomes, smooth ER, rough ER, lysosomes, microvilli and golgi Optical microscope not useful because1. Has low resolution/not high enough resolution;2. (Because) wavelength of light not short enough/too long;

Question 5

Describe the nucleus

Answer 5

Made up of the nuclear pore, nuclear envelope, chromatin and the nucleolus. Codes the proteins in the DNA to allow it to carry out its tasks

Question 6

Nuclear pore

Answer 6

Gaps in the nuclear envelope to allow larger molecules out of the nucleus such as mRNA

Question 7

Chromatin

Answer 7

DNA not sorted into chromosomes

Question 8

Nucleolus

Answer 8

Helps in producing ribosomes

Question 9

Mitochondrion

Answer 9

Job is to produce ATP, this releases energy. Provides energy for the cell, through aerobic respiration. Aerobic respiration occurs within the matrix

Question 10

Why do some cells have more mitochondrion?

Answer 10

They have a more active metabolism, need more energy

Question 11

Rough ER

Answer 11

Rough endoplasmic reticulum has ribosomes attached. Its job is to produce proteins/glycoproteins and to transport proteins

Question 12

Smooth ER

Answer 12

Smooth endoplasmic reticulum, found and attached to the nuclear envelope. The job is to produce lipids, steroids and carbohydrates. Also to store carbs

Question 13

Golgi Apparatus

Answer 13

These also produce glycoproteins and secretory enzymes as well as lysosomes. Modifies and stores lipids. Vesicles transport proteins or substances made by the golgi to inside or outside of the cell

Question 14

Lysosomes

Answer 14

Structures which contain enzymes produced by the golgi, these destroy weak or old cells or organelles.

Question 15

Ribosomes

Answer 15

Very small, site of protein synthesis

Question 16

Types of microscope

Answer 16

Light, transmission or scanning electron microscope

Question 17

Light microscopes

Answer 17

1500x magnification, easy to use. Used in schools. Light rays are used to see it. Problem - cannot see things inside of the cells as the wavelength is relatively big

Question 18

Electron microscope

Answer 18

Much smaller wavelengths. Uses electrons. SEM- electrons are reflected off the surface for a 3D image. 100,000x magnification. TEM - Electrons pass through the object, images are 2D, 500,000x magnification. The training and preparation is a excessive

Question 19

mm

Answer 19

x10^3

Question 20

um

Answer 20

x10^6

Question 21

nm

Answer 21

x10^9

Question 22

image size =

Answer 22

image size =actual size x magnification

Question 23

Magnification

Answer 23

MagnificationHow many times bigger an image is than the object

Question 24

Resolution

Answer 24

The smallest distance between two objects that means they can be seen as separate

Question 25

Eukaryotic cells

Answer 25

animal and plant cells

Question 26

Ultracentrifugation

Answer 26

Cell fractionation to break and rupture cells, done using a blender with the cells in a buffered, ice-cold and isotonic solution. It is then spun in the centrifuge causing the heaviest organelles to form a sediment and the rest form the supernatant

Question 27

What is the cell membrane made of?

Answer 27

Made of phospholipids with proteins floating in between.

Question 28

What is the membrane referred to as, why?

Answer 28

Fluid mosaic model because the phospholipids move around and are fluid.

Question 29

How is the membrane arranged?

Answer 29

The phospholipids are arranged in two layers. The phosphate heads are polar molecules and so are water-soluble whilst the lipid tails are non-polar so are not water - soluble. This means that the phospholipids are arranged with the heads near cytoplasm

Question 30

What do the proteins in the membrane do?

Answer 30

Proteins in the membrane line pores in the lipid layer. The polar groups of the protein molecules mean that substances that would not be able to penetrate the lipid layer (lipid insoluble) can still move through the membrane

Question 31

What do the polysaccharide chains in the membrane do?

Answer 31

membraneThese are attached to the proteins and are called glycoproteins and help with the recognition and interaction with other cells

Question 32

What about cholesterol in the membrane

Answer 32

Maintains fluidity and increases stability

Question 33

Functions of the membrane (6)

Answer 33

1. selectively permeable barrier2. structural, keeping the cell contents together,3. allows communication with other cells, 4. allows recognition of external substances, 5. allows mobility in some organisms 6. the site of various chemical reactions

Question 34

Cholera bacteria are prokaryotic cells. Give three structures found in prokaryotic cells but not in eukaryotic cells.

Answer 34

Capsule / glycocalyx / slime layer;Circular / ring of / non-linear DNA / DNA without histones; Plasmid;Flagellum;Pilus;Small / less dense / 70s ribosomes;

Question 35

Many different substances enter and leave a cell by crossing its cell surface membrane. Describe how substances can cross a cell surface membrane.

Answer 35

1 (Simple / facilitated) diffusion from high to low concentration / down concentration gradient;2 Small / non-polar / lipid-soluble molecules pass via phospholipids / bilayer;ORLarge / polar / water-soluble molecules go through proteins;3 Water moves by osmosis / from high water potential to low water potential / from less to more negative water potential;4 Active transport is movement from low to high concentration / against concentration gradient;5 Active transport / facilitated diffusion involves proteins / carriers;6 Active transport requires energy / ATP;7 Ref. to Na+ / glucose co-transport;

Question 36

Coeliac disease is a disease of the human digestive system. In coeliac disease, the microvilli are damaged.Although people with coeliac disease can digest proteins they have low concentrations of amino acids in their blood.Explain why they have low concentrations of amino acids in their blood.

Answer 36

Reduced surface area; (So) less absorption;(Membrane-bound) enzymes less effective; (So) proteins / polypeptides not digested;Cell membranes damaged;(So) Fewer / less effective carrier / channel proteins;Carrier / channel proteins damaged; (So) less absorption;

Question 37

Some students were advised in an experiment that they could improve the reliability of their results by taking additional readings. Explain how

Answer 37

Anomalies to be identified or the effect of anomalies to be reducedA mean to be calculated;

Question 38

Some cells lining the bronchi of the lungs secrete large amounts of mucus. Mucus contains protein.Name one organelle that you would expect to find in large numbers in a mucus-secreting cell and describe its role in the production of mucus

Answer 38

Organelle named; Function in protein production/secretion;eg1. Golgi (apparatus);2. Package/process proteins;OR3. Rough endoplasmic reticulum/ribosomes;4. Make polypeptide/protein/forming peptide bonds;OR5. Mitochondria;6. Release of energy/make ATP;OR7. Vesicles;8. Secretion/transport of protein

Question 39

An enzyme catalyses only one reaction. Explain why

Answer 39

1. (Enzyme has) active site2. Only substrate fits (the active site)