cell division- organisation, specialisation and stem cells

Question 1

state the levels of organisation

Answer 1

specialised cells, tissues, organs, organ system, organism

Question 2

Erythrocytes are red blood cells, describe how its adapted to perform its function.

Answer 2

-biconcave shape to increase surface area to volume ratio to carry more oxygen
-no nuclei, more space for haemoglobin
-flexible to squeeze through narrow capillaries

Question 3

neutrophils are a type of white blood cell, describe how its adapted to perform its function

Answer 3

• multi-lobed nucleus which makes it easier to squeeze through small gaps to get to the site of infection.
  -cytoplasm contains many lysosomes which contain enzymes to fight pathogens

Question 4

how are sperm cells adapted to carry its genetic information to the ovum?

Answer 4

-flagellum for movement
-lots of mitochondria, more energy
-acrosome (head) contains many digestive enzymes. These enzymes digest the protective layer of the ovum.

Question 5

how are palisade cells in the mesophyll adapted to perform its function?

Answer 5

-lots of chloroplasts to absorb light
-chloroplast can move within the cytoplasm, more light absorbed
-rectangular shape means they can be more closely packed
-thin cell walls, increase rate of diffusion
-large vacuole to maintain turgor pressure.

Question 6

how are root hair cells adapted to perform its function?

Answer 6

-long extensions, increases surface area for maximum absorption of water and minerals.

Question 7

how are guard cells adapted to perform its function?

Answer 7

when guard cells lose water, they change shape, closing the stomata, preventing further water loss

Question 8

what is a tissue?

Answer 8

a collection of specialised cells with a particular function

Question 9

what are the four main categories of tissue in animals?

Answer 9

-nervous tissue: supports transmission of electrical impulses
-epithelial tissue: covers internal and external body surfaces
-muscle tissue: contraction
-connective tissue: hold tissues together or transport medium

Question 10

squamous epithilium tissue is made of specialised squamous epithelial cells. It forms the lining of the lungs, describe how it is adapted to perform its function.

Answer 10

-one cell thick, rapid diffusion of oxygen

Question 11

ciliated epithelium tissue is made of ciliated epithelial cells. They are found on the lining of the trachea. How is it adapted?

Answer 11

-cells have hair like structures called cilia which move in a rhythmic matter
-contain goblet cells which release mucus to trap unwanted particles

Question 12

cartilage is a connective tissue, describe how its adapted?

Answer 12

-contains fibres of the protein elastin and collagen
-firm and flexible, prevents bone rubbing on bone.

Question 13

what are the different types of tissue in plants?

Answer 13

-epidermis tissue: adapted to cover plant surfaces
-vascular tissue: adapted to transport water and nutrients.

Question 14

how is epidermis tissue adapted?

Answer 14

-waxy cuticle to prevent water loss
-stomata and guard cells allow diffusion of oxygen and carbon dioxide.

Question 15

how are xylem tissue adapted?

Answer 15

contains lignin which provide structural support to transport water and minerals.Dead cells.

Question 16

how are phloem tissue adapted?

Answer 16

It is composed of columns of sieve tube cells separated by sieve plates. Phloem transports nutrients.

Question 17

what is an organ?

Answer 17

collection of tissues, adapted to perform a particular function

Question 18

what happens if stem cells divide too slow?

Answer 18

ageing faster

Question 19

what happens in stem cells divide too fast?

Answer 19

tumours, cancer

Question 20

what is potency?

Answer 20

a stem cells ability to differentiate into any different cell types

Question 21

what is totipotent?

Answer 21

stem cells which can divide into any cell type e.g a zygote. They can eventually produce a whole organism.

Question 22

what is pluripotent?

Answer 22

stem cells which can form all tissue types but not whole organisms. They are present in early embryos.

Question 23

what is multipotent?

Answer 23

stem cells which can only form a range of cells with a certain type of tissue. E.g stem cells in bone marrow.

Question 24

why do red blood cells have a short life span?

Answer 24

because they have a lack of nucleus and organelles therefore they need to be replaced regularly by stem cells in the bone marrow.

Question 25

where are the animal stem cells sourced?

Answer 25

-embryonic stem cells -cells present in the very early stages on embryo development are totipotent but after 7 days they are in the pluripotent state.
-tissue (adult) stem cells- multipotent, can be found from bone marrow and umbilical cord

Question 26

where are the plant stem cells sourced?

Answer 26

meristematic tissue which is found where ever growth occurs (e.g roots and shoots).

Question 27

name potential uses of stem cells in medicine?

Answer 27

-medical research
-transplants to repair damaged tissue