D3 Continuity and Change : Organisms

Question 1

hermaphrodites

Answer 1

An organism with both male and female reproductive organs.

Question 2

what makes up the menstrual cycle

Answer 2

ovarian and uterine cycle

Question 3

3 stages of ovarian cycle

Answer 3

• follicular phase
• ovulation
• luteal phase

Question 4

3 stages of uterine cycle

Answer 4

• menstruation
• proliferation phase
• secretarial phase

Question 5

double fertilisation

Answer 5

The two fertilisation events that occur: fusion of the first male gamete with the nucleus of the egg cell, and the fusion of the second male gamete with the two polar nuclei present in the central cell.

Question 6

self- incompatibility

Answer 6

The inability of hermaphroditic plants to produce zygotes after self-pollination.

Question 7

germination

Answer 7

The process that begins with the uptake of water by the seed and ends with the emergence of the radicle.

Question 8

Gametogenesis

Answer 8

Formation of haploid gametes - spermatogenesis and oogenesis

Question 9

corpus luteum

Answer 9

A temporary organ formed in each menstrual cycle from the ruptured follicle which secretes hormones.

Question 10

zona pellucida

Answer 10

A layer on the outside of the oocyte made of glycoproteins. It is present in the unfertilised cell as well as in early embryo development.

Question 11

corona radiata

Answer 11

A layer of follicular cells that surrounds the ovum.

Question 12

acrosome

Answer 12

An organelle at the head of the sperm that contains digestive enzymes that aid fertilisation.

Question 13

capacitation

Answer 13

Biochemical and physiological changes undergone by the sperm in order to fertilise an egg.

Question 14

triple fusion

Answer 14

The fusion of a single male gamete with the two polar nuclei present in the central cell.

Question 15

endosperm

Answer 15

Tissue that surrounds the developing embryo of flowering plant seeds and nourishes them.

Question 16

acrosome reaction

Answer 16

Hydrolytic enzymes released by the acrosome digest and soften the zona pellucida, assisting fertilisation.

Question 17

polyspermy

Answer 17

The fusion of more than one sperm with the egg.

Question 18

cortical reaction

Answer 18

A mechanism that prevents polyspermy and involves the release of cortical granules from the fertilised egg.

Question 19

cleavage

Answer 19

A series of rapid cell divisions undergone by a zygote.

Question 20

trophoblast

Answer 20

Cells that will become the placenta

Question 21

inner cell mass

Answer 21

Cells within the blastocyst that will become the embryo.

Question 22

haploid

Answer 22

A haploid nucleus contains a single set of chromosomes. Gametes are haploid.

Question 23

diploid

Answer 23

Cells that contain two copies of each autosome and two sex chromosomes. Diploid cells have an even number of chromosomes.

Question 24

self pollination

Answer 24

The transfer of pollen grains to the stigma of the same flower or to the stigma of another flower on the same plant.

Question 25

cross pollination

Answer 25

The transfer of pollen grains from one flower on one plant to the stigma of another flower on another plant.

Question 26

P generation

Answer 26

Parent generation of a genetic cross.

Question 27

F1 generation

Answer 27

F1 are the offspring from the P generation; F2 are the offspring produced from crossing F1 parents.

Question 28

homologous chromosomes

Answer 28

A pair of chromosomes of the same type (one comes from the mother and one comes from the father).

Question 29

allele

Answer 29

A variant or version of a gene.

Question 30

phenotypical plasticity

Answer 30

The ability of an organism to exhibit variations in its physical characteristics or traits in response to environmental influences.

Question 31

codominant

Answer 31

Two alleles are both expressed equally.

Question 32

incomplete dominance

Answer 32

A third phenotype that is intermediate between the dominant and recessive can be produced.

Question 33

non disjunction

Answer 33

The failure of homologous chromosomes or sister chromatids to separate during cell division.

Question 34

sex linked genetic disorders

Answer 34

A condition caused by a mutation on the X chromosome.

Question 35

gene pool

Answer 35

The combination of all the genes that are present in a reproducing population.

Question 36

discrete variation

Answer 36

Phenotypes that have distinct categories, for example, blood type A, B, AB or O.

Question 37

polygenic inheritance

Answer 37

When more than one gene controls a characteristic, for example, the inheritance of skin colour.

Question 38

continuous variation

Answer 38

Phenotypes that show a wide variety between two extremes in a population, for example, height.

Question 39

linked genes

Answer 39

Genes on the same chromosome that are usually inherited together.

Question 40

unlinked genes

Answer 40

Genes on different chromosomes that assort independently.

Question 41

independant assortment

Answer 41

The separation of homologous chromosomes and sister chromatids being independent of their pair during meiosis due to random orientation.

Question 42

monohybrid cross

Answer 42

A cross between two individuals of the same species that considers the inheritance of a single trait.

Question 43

dihybrid cross

Answer 43

A cross between two individuals of the same species that considers the inheritance of two traits.

Question 44

homeostasis

Answer 44

The ability of the body to seek and maintain equilibrium and maintain conditions optimal for survival.

Question 45

Exocrine

Answer 45

The system for secreting substances through ducts onto surfaces of the body. Examples are sweat and digestive enzymes.

Question 46

Endocrine

Answer 46

The system for secreting hormones from glands into the blood. These hormones help control body functions.

Question 47

nephrons

Answer 47

The functional unit of the kidney that filters blood, reabsorbs useful substances and excretes waste products in the form of urine.

Question 48

Bowman's capsule

Answer 48

A cup-shaped structure in the nephron of the kidney that surrounds the glomerulus and collects the filtrate.

Question 49

afferent arterioles

Answer 49

Blood vessels that supply oxygenated blood from the renal artery to the kidney for filtration at high pressures.

Question 50

glomerulus

Answer 50

A network of capillaries in the Bowman's capsule of the kidney that filters blood to form urine.

Question 51

efferent arterioles

Answer 51

Narrow blood vessels that carry blood away from the glomerulus in the kidney. They restrict blood flow to generate the pressure needed for filtration.

Question 52

proximal convoluted tube

Answer 52

A section of the nephron in the kidney that reabsorbs most of the filtered water and electrolytes, as well as amino acids and glucose.

Question 53

loop of henle

Answer 53

A section of the nephron in the kidney that creates a concentration gradient in the renal medulla and plays a key role in the reabsorption of water and electrolytes.